PART II
Policies, Agreements, Joint Instructions, and Joint Agencies

Contents

Chapter V--	Coastal Frontier Defense.
VI--	Joint Overseas Expeditions.
VII--	Regulations, Maneuver Rules, and Umpire Instructions for Joint Army and Navy Exercises.
VIII--	Agencies for Effecting Coordination.
IX--	Communications.

[B L A N K]

Part II
Policies, Agreements, Joint Instructions, and Joint Agencies

Chapter V
Coastal Frontier Defense

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Contents

Para- graph	Subject	Page
	Section I--Introduction and Definitions
24	Purpose of publication	27
25	Purpose of coastal frontier defense	27
26	Definitions:
	A coastal frontier	28
	Coastal frontier defense	28
	The naval district	28
	Naval local defense forces	29
	A naval base	29
	An army	29
	A corps area	29
	A coast artillery district	29
	A sector	30
	A subsector	30
	Coastwise sea lanes	30
	The coastal zone	30
	A defensive sea area	30

Para- graph	Subject	Page
	Definitions--Continued.
	A defensive coastal area	30
	The outer harbor area	31
	The harbor channel area	31
	The inner harbor area	31
	An inshore patrol	31
	An offshore patrol	31
	An escort force	31
	A coastal force	31
	A harbor defense	31
	A beach defense	31
	Army outpost or covering forces	32
	Army reserves	32
	An aircraft warning service	32
	Section II--Possible Enemy Operations
27	Major operations	32
28	Minor operations	34
29	General	34
	Section III--Categories of Defense and Requirements and Means to be Provided
30	Degree of preparation	38
31	Categories of defense:
	Category A	38
	Category B	39
	Category C	39
	Category D	39
	Category E	40
	Category F	40
	General	40
32	Requirements and means to be provided:
	General requirements	41
	Defensive operations required	41

Para- graph	Subject	Page
	Section III-Continued
	Requirements and means to be provided--Continued.
	Means available	42
	The Fleet	42
	Naval local defense forces	42
	The Army forces	42
	Mobile forces	42
	Harbor-defense forces	42
	Relation of the Fleet to coastal frontier defense	42
	Relation of Army mobile forces to coastal frontier defense	43
	Relation of Army air forces to coastal frontier defense	43
	Naval local defense forces	45
	The inshore patrol	45
	The offshore patrol	47
	The escort force	47
	A coastal force	48
	Defensive coastal areas	48
	Extent	48
	Harbor defenses	48
	Communications	50
	General	51
	Defensive sea areas	51
	Defense against landing attacks	52
	Measures and operations demanded of the defense	52
	Steps in the joint organization and operations against landing attack	52
	Obstacles-types	54
	General	54
	Obstructions	54
	Torpedo-defense nets	54
	Antisubmarine nets	55
	Booms	55
	Mines	55
	Section IV--Organization and Command
33	Joint organization and command	55
34	North Atlantic coastal frontier:
	Boundaries	55
	Commanders	56
	Sectors	56

Para- graph	Subject	Page
	Section IV--Continued
35	Southern coastal frontier:
36	Pacific coastal frontier:
37	The Great Lakes coastal frontier:
38	Defensive coastal areas	60
39	Defensive sea areas	61
	Section V--Planning
40	Means to facilitate joint planning	61
41	Collaboration in joint planning	62
42	Details of joint coastal frontier defense plans	63

Chapter V
Coastal Frontier Defense

Section I
Introduction and Definitions

24. Purpose of publication.--The purpose of this publication is to present the principles and measures necessary for the effective joint organization and conduct of operations in coastal frontier defense and the method of planning involved and the responsibilities of the two services in connection therewith, in order to insure the most effective cooperation and coordination between Army and Navy forces participating therein. See pars. 13 and 19, pt. I, Joint Acton of the Army and the Navy.)

25. Purpose of coastal frontier defense.

    1. The purpose of a joint organization and measures for coastal frontier defense is to provide more effectively for our national defense.

    2. Specifically, the measures of operations in coastal frontier defense are for the purpose of:

       1. Protecting shipping in the coastal zones;

       2. Protecting our military and civil installations and facilities;

       3. Preventing invasion of United States territory from overseas;

       4. Insuring the security of those portions of our coastal frontiers which are vital to military, industrial, and commercial operations.

26. Definitions.--In order to provide a common basis of understanding between the Army and the Navy in the employment of forces in coastal frontier defense, the following definitions of terms employed are herby established:

    1. A coastal frontier is a geographical division of our coastal area established for organization and command purposes, in order to insure the effective coordination of Army and Navy forces employed in coastal frontier defense. The coastal frontier of a group of islands shall completely surround such group or shall include that part of the group which can be organized for defense and command purposes. Within each coastal frontier an Army officer and a naval officer will exercise command over all Army forces and Navy forces, respectively, assigned for the defense of these divisions. Coastal frontiers are subdivided for command purposes into sectors and subsectors.

    2. Coastal frontier defense is the organization of the forces and matériel of the Army and the Navy assigned to provide security for the coastal frontiers of continental United States and its overseas possessions.

    3. The naval district is a military and administrative command ashore established for the purpose of decentralizing the Navy Department's functions with respect to the control of shipping in the coastal zones and the shore activities outside the Navy Department proper, and for the further purpose of centralizing under one command within the district and the waters thereof:

       1. For military coordination, all naval activities; and

       2. For administrative coordination, all naval activities with specific exceptions.

       The primary purpose in view is to provide for naval mobilization and logistic support of the Fleet and to utilize the district naval forces in the joint organization to provide security for the coast and for shipping in the coastal zones. The limits of the naval districts are laid down in the Navy Regulations. These limits extend to seaward so as to include the coastwise sea lanes. Each naval district is commanded by a designated commandant who is the direct representative of the Navy Department, including its bureaus and offices, in all matters affecting district activity.

4. Naval local defense forces consist of naval forces, including Coast Guard and Lighthouse Service, afloat and ashore, attached to a naval district and under the command of the commandant of the district. These forces are not a part of the Fleet.

5. A naval base is a center from which men-of-war can operate and be maintained.

6. An army is a military organization or unit composed of a headquarters, a body of auxiliary troops and trains called army troops, and two or more corps temporarily assigned, the number of corps depending upon the nature of the service required. To these may be added a special assignment of GHQ aviation, GHQ reserve artillery, cavalry divisions, and other troops varying in number and composition according to the task assigned. As thus constituted, an army has both territorial and tactical functions. It is the largest self-contained military unit and may act independently or may form part of a group of armies or other higher organization.

7. A corps area is a territorial and administrative command within the continental area of the United States, established for purposes of administration, training, and tactical control during peace time and for the conduct of mobilization and other functions of the zone of the interior in war.

8. A coast artillery district is a military command within a certain corps area which contains harbor defenses. I it established for the purpose of decentralizing the corps area commander's functions of discipline, instruction, and routine training of the coast artillery troops within the corps area. When frontier commands sectors, and subsectors come into active existence, coast artillery districts as such cease to exist and all coast artillery troops, including the district staff, located within the frontier, sector, or subsector automatically become part of the frontier, sector, or subsector command as the case may be. The coast artillery district commander automatically becomes a coastal frontier or sector commander, as prescribed in section IV of this chapter and/or in specific war plans. As frontier commander, he is responsible to the army commander as long as the latter retains tactical responsibility within the area. Upon departure of the army commander, the frontier commander is responsible directly to the commanding general of the field forces.

9. A sector is one of the subdivisions of a coastal frontier command.

10. A subsector is one of the subdivisions of a sector command.

11. Coastwise sea lanes are the water areas adjacent to the seacoast that include all the usually traveled routes of coastwise shipping.

12. The coastal zone is the whole area of the navigable waters adjacent to the seacoast and extends seaward to cover the coastwise sea lanes and focal points of shipping approaching the coast.

13. [»] A defensive sea area is a portion of the coastal zone, usually including the approach to an important port,harbor, bay, or sound, within which,if such area be publicly proclaimed and neutrals notified, international practice tacitly permits the belligerent to shipping from minefields, obstructions, or the danger of being considered hostile. A defensive sea area is established by proclamation of the President and by notification to neutrals. The limits of the defensive sea area must be contained in the proclamation, and should be such that control of shipping in the area is within the capacity of the available naval local defense forces.

    [»]

14. [»] A defensive coastal area is a part of a coastal zone and of the land and water area adjacent to and inshore of the coast line within which defense operations will involve both Army and Navy forces, and in consequence require effective coordination. A defensive coastal area pertaining to a fortified harbor includes the outer harbor area, the harbor channel area, and the inner harbor area; its outer limits, which are specified in each case by joint plans, are the outer limits of the ranges of the shore defense batteries. When a defensive sea area and a defensive coastal area coexist in any one locality, the water area of the defensive coastal area which lies between its outer limits and the inner limits of the harbor channel area, shall be considered superimposed upon a like portion of the defensive sea area, without in any way detracting from the Army's responsibility for the direct defense of the coast. Defense activities in that portion of a defensive sea area not included within a defensive coastal area, are essentially naval in character but are of immediate interest to the Army as by such means are disclosed the presence and indicated objectives of enemy forces.

15. The outer harbor area is the water area which extends to seaward from the outer exits of the entrance channels to a fortified harbor and lies within the range of the harbor defense batteries.

16. The harbor channel area is the water area which lies between the outer harbor area and the inner harbor area, and which comprises all the entrance channels to the harbor.

17. The inner harbor area is the entire water area of a fortified harbor inside the inner entrance of all the entrance channels to the harbor.

18. [»] An inshore patrol is a part of the naval local defense forces operating generally within a defensive coastal are and controlling shipping within a defensive sea area.

19. An offshore patrol is a part of the naval local defense forces operating and patrolling the coastal zone outside of those areas assigned to the inshore patrol.

20. An escort force is a part of the naval local defense forces charged with the duty of protecting convoys within a naval district waters,

21. A coastal force is a naval force which may be organized to operate within the coastal zone to meet a special situation in which naval local defense forces are inadequate to carry out the Navy's functions in coastal frontier defense.

22. A harbor defenseis an administrative and tactical Army command, comprising the armament and accessories, including antiaircraft armament, controlled mines and supporting aircraft, with the personnel for manning, provided for the defense of a harbor or other water area. Harbor defenses exist to provide on the outbreak of war an effective seaward defense of important strategic points, such as large centers of population, important commercial centers, navy yards, coaling or fueling stations, locks and dames; to deny the enemy entrance to or occupation of a harbor or other waters which might serve as a base for land or naval operations, or both; and to keep the enemy at such distance from the entrance to a waterway that our naval forces may debouch therefrom and take up a battle formation with the lest hostile interference.

23. A beach defense is that part of the Army ground organization for defense against landing attacks which is located at or near the beach for resistance at the water's edge. It consists of a series

of organized tactical localities in rear of those sections of the shore line where landings are likely to be made, and includes barbed-wire entanglements and other obstacles below and above the water line. Beach defense may be organized both within and outside of defensive coastal areas.
24. Army outpost or covering forces are mobile Army forces allotted to subsectors, sectors or frontiers, to provide security against raiding operations, and to cover the points of landing in a direct attack prior to the assembly of Army reserves, or additional forces.

25. Army reserves are mobile Army forces drawn from any available source and held in readiness to be sent to any part of the frontier or frontiers that may be threatened by an enemy attack.

26. An aircraft warning service is a communication and intelligence service which forms part of the communication and intelligence service of the frontier defense. Its purpose is to warn centers of population, industrial plants, public utilities, and military and naval establishments of the approach of hostile aircraft, and to alert Air Corps units and antiaircraft artillery units. It consists essentially of observers, of information centers for plotting the courses and distributing information of approaching hostile planes, and of the necessary communications.

Section II
Possible Enemy Operations

27. Major operations.

    1. When control of vital sea areas cannot be maintained due to our inferiority in naval power, destruction of our Fleet, or to its absence in distant waters, serious attacks against our coastal frontiers are possible and may be expected against strategically important areas when the enemy possesses the requisite force and marine transportation. These attacks may be of major proportions and may have as their object any one or more of the following:

       1. The securing of a beachhead as a point of departure for an invasion;

       2. The securing of an area for use in conjunction with other military operations or in connection with the destruction

of our shipping and/or our military and/or industrial installations and facilities;
3. The securing of an area for use as a naval base;

4. The securing of an area in order to deny its use to our forces;

5. The securing of an area for use as an air base, for air raids or for the establishment of local air superiority;

6. The blockading of our seacoast against shipping and/or against our naval forces.
2. Landing attacks in force--namely, those involving large invading forces--presuppose that the attacker has local control of the sea area, and also that he has the power to establish locally and for the necessary period of time a definite air superiority. The aviation with the enemy fleet may be insufficient for this purpose, so that the enemy may have to resort to the establishment of air bases and the concentration thereat of the necessary land-based aircraft. The enemy will, however, endeavor to make the maximum use of tactical surprise; he may further be expected to avoid fortified areas so far as may be consistent with his mission and objective.

3. Where a landing attack in force involves operations against fortified areas, the following steps, either distinct or merged together, may be anticipated, although the desirability for tactical surprise may cause complete omission of any preliminary reconnaissance:

   1. Reconnaissance in force, in which all types of ships may be employed with carrier-based aviation either to determine what defense elements are manned and what resistance is to be expected, or to clear the way for heavier ships. It will be a period of intensive reconnaissance, possibly accompanied by mine sweeping, minor raids with limited objectives, and feints.

   2. Bombardments by aircraft and long-range armament of the heavier ships to neutralize such land artillery as may be effective in opposing the landing.

   3. Support of the landing by the fire of naval ships, assisted by aviation, to cover debarkation from the transports, approach to the beach and landing thereon.

4. Employment of the requisite force to secure harbor facilities suitable for the debarkation of the heavy troop equipment and for the establishment of a base.
4. When a landing attack in force does not involve operations against a fortified area, the enemy may be expected to make the maximum use of tactical surprise, in order to allow his troops to reach the beach with a minimum concentration against them. Such reconnaissance as the enemy may decide to make will probably be on a wide front and be followed without loss of time be debarkation and the attack of the beaches under such supporting fire as may be available. The attacker may be expected to land on a broad front in several waves in an endeavor to establish, as quickly as possible, a beachhead to a depth of the effective range of light artillery.
28. Minor operations.--So long as our Fleet retains command of the sea, or so long as such command remains in dispute, our coastal frontiers bordering upon the sea areas in which our FLeet is operating may be regarded as protected against a major attack. However, neither command of the sea nor superiority of our air forces, in any given locality, can be counted upon to prevent surprise attacks or raids by minor naval forces for the accomplishment of minor missions. These hostile operations may have as their objectives the following:

    1. Destruction of military and industrial installations and facilities.

    2. Destruction of shipping in the coastal zone.

    3. The gaining of minor advantages incident to controlling the sea, or for reconnaissance, bombardment, mining, countermining, demolition, or in operations preliminary to joint major operations.

    4. The observation or blockade of our naval forces while they are lying under the shelter of fortifications.

29. General.

    1. The execution of naval missions or the performance of functions of navies in war may lead to offensive operations from the sea against land areas. Such operations will usually be in the nature of joint expeditions of Army and Navy forces.

    2. Operations by naval forces against shipping may involve a blockade of certain localities and attacks on shipping in the coastal zone, in approaches to harbors, and even in harbors.

3. The employment of naval forces alone in minor operations against our coastal frontiers, and not incident to joint operations, will, in general, be limited to bombardment from ships or by aircraft of positions not well covered by defensive means, small landing raids for demolition purposes, and feints.

4. The employment of naval forces alone in operations preliminary to joint operations may include all forms of reconnaissance; the seizure of land bases for aviation fields preparatory to supporting a landing; blockading, mining,and countermining operations; attacks on outer defense elements of a fortified area; and feints.

5. Bombardments of land positions by gunfire of naval forces may be undertaken under special circumstances, but any naval force engaging in such bombardments accepts hazards which are so obvious that they have to be justified by circumstances. The employment of capital ships, for instance, in the bombardment of fortified land positions is not likely to be undertaken if such action jeopardizes in any appreciable degree the ability of the bombarding force later to meet on terms of at least equality the enemy naval forces. Ships and their personnel are much more vulnerable to artillery fire than the corresponding material and personnel of land artillery and other defensive shore installations are to fire form ships. The ammunition normally carried by ships is not well suited to the attack of land targets. In addition to the hazards incident to land artillery fire directed against ships engaged in bombarding shore positions, there is the added hazard of attack by land-based aircraft, of submarines, and of mines. Special opportunity is given for the efficient use of these added weapons against the bombarding ships by the fact that the operation is a localized one. Under modern conditions, in an attack upon a fortified harbor, no naval force of capital ships will attempt to force the passage of, or to run by, the fortifications except under most unusual circumstances, when the end in view is vital to the success of the campaign. This applies whether or not enemy land forces are operating on shore against such a fortified harbor.

6. In a discussion of possible enemy naval operations and of possible defensive and offensive air operations, the circumstances of the season and the weather must not be lost sight of, since varying conditions of these two elements have a marked effect on the powers and limitations of naval attacks. During the period of heavy storms,

enemy naval operations will probably come to a standstill. Northern winter weather will, as a rule, considerably restrict naval operations, limiting them in the general case to observation and reconnaissance, and to ineffective offensive action against the obstacles of the defense, and precluding any but very minor landing operations. Thick weather may be advantageous to the enemy in covering minor operations against outlying elements of the defense; but heavy fog will generally suspend enemy offensive operations.
7. During periods of heavy storm, low visibility, or low ceiling, air patrol and air observation will probably be unreliable, offensive air operations may be impossible, and air operations may even have to be suspended entirely.

8. Consideration of the preceding paragraphs indicates that the forms of hostile action which an enemy may employ either singly or in combination, against, or in the vicinity of, our coastal frontiers, may include any one or more of the following operations:

   1. Attacks on shipping in the coastal zone or in approaches to harbors.

   2. Attacks on naval forces of the defender, either off the coast, entering a harbor, while inside the harbor, or while debouching therefrom.

   3. Air bombardments of the seacoast and contiguous areas from forces well out to sea.

   4. Blockading of the seacoast against shipping and/or against our naval forces.

   5. Mine laying off the seacoast or the entrance of harbors.

   6. Naval raids on undefended or lightly defended coastal areas, primarily for demolition purposes and involving air or gun bombardments, or landings with limited objectives of forces composed of sailors and marines without intent to occupy any part of the frontier for any considerable period of time.

   7. Feints, involving part or all of the operations of (3), (4), (5), and (6) above.

   8. A broad general reconnaissance, especially by aircraft, to determine the nature, the extent, and location of defending forces.

9. Local reconnaissance, either--

   1. To determine the practicability of taking advantage of surprise and an unprepared state of defense, in order to secure an area before the defending forces are ready;

   2. As part of an attempted landing; or

   3. In force against a fortified area to determine its state of preparedness, or to clear the way for a major attack.

10. Seizure of land bases for air fields preliminary to further operations.

11. Bombardment by gunfire and by aircraft for the neutralization of land artillery and for the destruction of important shore objectives.

12. Minor attacks, possibly involving small landings, against outlying elements of the defense.

13. Mine sweeping, countermining, and attempts to destroy nets or other obstacles.

14. Torpedo fire into harbors.

15. Blocking action against harbor entrances.

16. Penetration by naval vessels into a harbor or water area.

17. Major landing operations supported by rapid-fire guns on ships and by aviation.

18. Seizure of harbor facilities for debarkation of heavy equipment and for the establishment of a base.
9. The parts played by the different types of naval craft in the above operations include:

   1. By surface craft.--Information and reconnaissance; seizure or destruction of shipping; combat with naval vessels; mining or countermining;l minesweeping; launching air operations; blockade; closing harbors or channels; clearing underwater obstacles; attacking nets; cutting cables; torpedo attacks on ships outside or inside harbors; laying a smoke screens; gun bombardment; making feints; forcing a passage; and making and covering landings either for demolition purposes or for minor raids or raids in force.

2. By submarines--Attacks on combatant vessels; information and reconnaissance; blockade, raids on nets or other obstacles; cutting cables; mining; minor bombardments; making feints; and minor landings.

3. By aircraft.--Information and reconnaissance; attacking ships and shore objectives with machine-gun fire and/or high-explosive bombs; destroying obstacles; landing observers or spies; gaining superiority in the air; spotting gunfire; and laying smoke screens.

Section III
Categories of Defense and Requirements and Means to be Provided

30. [»] Degree of preparation.--The degree of preparation in coastal frontier defense and the frontier defense measures to be taken, including the strength of the forces to be provided, depend upon the enemy and the character of the enemy operations to which coastal frontiers may be subjected in the early stages of a war. For the purpose of indicating the extent of the frontier defense measures to be taken under specific situations, categories of defense are established as listed below. Decisions as to the "category of defense" required for each coastal frontier are included in all joint basic war plans except those for wars of a minor nature. These decisions constitute a directive to the Army and Navy commanders of the joint organization for coastal frontier defense as to the extent of the frontier defense measures to be taken. They likewise constitute a directive to the War and Navy Departments as to the allocation of the means required for this defense. Defensive sea areas will be proclaimed in time of actual or impending war as necessitated by the nature of the war and the probable enemy.

31. Categories of defense.

    1. Category A.--Coastal frontiers that probably will be free from attack, but for which a nominal defense must be provided for political reasons. Under this category,l only a sufficient part of the gunfire elements of harbor defenses will be manned in the strength required to create a show of preparedness. The strength required will be that

considered necessary to repel small naval raids. A nominal offshore patrol will be maintained.
2. Category B.--Coastal frontiers that may be subject to minor attacks. Under this category, the harbor defenses will be provided with one manning relief, and a part of the obstacles will be prepared but not put in place. Certain defensive sea areas may be established and a limited offshore patrol may be instituted, with a limited control of shipping entering and leaving harbors.

3. Category C.--Coastal frontiers that in all probability will be subject to minor attack. Under this category, the coastal defense area should be provided, in general, with the means of defense, both Army and Navy, required to meet the following enemy naval operations: those incident to controlling the sea; those against shipping; and minor attacks against land areas. The harbor defenses should be fully manned and air support arranged. Long range air reconnaissance will be provided, if practicable. If sufficient forces are available, outposts will be established outside of harbor defenses along the sensitive areas of the shore line. The inner mine barrages will, in general, be established; a full inshore patrol and complete control of shipping will, as a rule, be instituted; and certain outer mine barrages and defensive sea areas may be established, and a limited offshore patrol instituted.

4. [»] Category D.--Coastal frontiers that may be subject to major attack. Under this category, the coastal defense areas should, in general, be provided with the means of defense, both Army and Navy, required to meet enemy naval operations preliminary to joint operations. All available means of defense will generally find application, and a stronger outpost and a more extensive patrol, inshore and offshore, than for Category C, will be required. Under this category certain defense sea areas will be established. In addition, an antiaircraft gun and machine-gun defense of important areas outside of harbor defenses should be organized; general reserves should be strategically located so as to facilitate prompt reinforcement of the frontiers; and plans should be developed for the defense of specific areas likely to become theaters of operations. Long range air reconnaissance will be provided and plans made for use of the GHQ air force.

5. [»] Category E.--Coastal frontiers that in all probability will be subject to major attack. Under this category, in addition to the measures required for Category D, there will be required generally the concentration of the troops necessary to defend the area against a serious attack in force, together with additional naval forces to provide intensive inshore and offshore patrols. Defense sea areas will be established. Air defense will be provided as in Category D. All or a part of the GHQ air force may be ordered to the threatened area to operate either under direct control of Army GHQ or under that of the Army commander of the theater of operations or frontier.

6. Category F.--Possessions beyond the continental limits of the United States which may be subject to either minor or major attack for the purpose of occupation, but which cannot be provided with adequate defense forces. Under this category, the employment of existing local forces and local facilities will be confined principally to the demolition of those things it is desirable to prevent falling into the hands of the enemy.

7. General.

   1. Where Categories D and E are applicable initially, local defense plans should provide for the initial employment of such forces of the Army and the Navy as may be required in addition to those forces which are ordinarily available for the initial defense of the coastal frontier in question, and which can be diverted from the mobilization and concentration of the Army forces, from the United States Fleet, and from other naval forces, during the period of mobilization and concentration, without materially interfering with or seriously delaying the operations to be undertaken in the principal theater of operations.

   2. Under all categories of defense, the Army coastal frontier or Army sector commander is responsible for the antiaircraft defense within the corps area and naval district extending inland from the frontier or sector, such antiaircraft defense to include an aircraft warning service. Cases involving the antiaircraft defense of Army GHQ airdromes and those where one corps area borders on two coastal frontiers, will be specifically covered in appropriate Army strategical plans.

32. Requirements and means to be provided.

    1. General requirements.

       1. The proximity of important cities and industrial areas to certain of our seacoast and lake frontiers and the consequent vulnerability of these places to attack, as well as the importance to the Nation of our shipping and its related industries, and the fact that our coastal bases are the mainsprings of naval action, make the protection of these frontiers in time of war a highly important part of the national defense.

       2. [»] Positive security, to include harbor defenses, has been provided for certain areas, the fixed armament of which has been or is being installed during peace time. Depending upon the liability of these areas to attack, and upon the character of such attack, defensive coastal areas have been designated and defensive sea areas should be designated in order to ensure the security of these important areas and the security of the shipping within their waters.

       3. In other respects, a minimum land and sea defense should be contemplated for our whole coastal frontier on the outbreak of war, and should involve the employment of only such parts of the means of defense as are required under the situation. In some situations, involving only minor enemy operations, it may be necessary to organize the beach defense for certain localities. Other situations involving more serious enemy attacks will require that the means of defense be successively augmented.

    2. Defensive operations required.--From a study of possible enemy operations, it appears that the defense of our coastal frontiers should take into consideration the following:

       1. The observation of the coastal frontier and the sea beyond as far as circumstances permit or seem to demand.

       2. The protection of shipping in waters adjacent to the seacoast.

       3. The attack on enemy vessels in waters adjacent to the seacoast.

       4. The resistance to enemy approach to the seacoast.

5. The protection of the seacoast, and especially strategic harbors, against raids.

6. The defeat of enemy landing attacks on the seacoast, including the provision of defensive installations on shore and in the waters adjacent thereto.

7. The initiation of counteroffensive operations to eject a landed enemy.
3. Means available.--Under the above conception of defensive operations that may be required to coastal frontier defense, the means that may be made available in time of war include--

   1. The Fleet, the employment of which, in accordance with the strategic situation, may keep the enemy away from our coastal frontiers.

   2. Naval local defense forces, which control the water areas within a naval district, conduct naval operations against enemy forces in the naval district waters, and cooperate with and support the Army in repelling attacks on coastal objectives.

   3. The Army forces.

      1. [»] Mobile forces, including air forces, to provide the covering or outpost forces for the initial coastal frontier defense organization and likewise the additional forces necessary to defeat landing attacks and air attacks and to carry out the Army functions specified in paragraph 13a.

      2. Harbor defense forces for maintenance and operation of essential harbor defenses designed to prevent ingress into areas, including the air space thereof covered by these defenses.

4. Relation of the Fleet to coastal frontier defense.-The strategic freedom of action of the Fleet must be assured. This requires that coastal frontier defense be so effectively conducted as to remove any anxiety of the Fleet in regard to the security of its bases. In the case of hostile major overseas movements directed against our coasts, the Fleet, if present and free to act, will be a powerful factor for ensuring the security of its bases and our coasts, and, if it engages the enemy, should be supported by all the land-based aircraft available.

5. Relation of Army mobile forces to coastal frontier defense.--The Army, in its responsibility for the direct defense of the coast, must be prepared to meet successfully any attack directed against any part of our coastal frontiers. This responsibility and the possibility that naval strategy may demand the presence of the Fleet in another theater of operations make it necessary for the Army to provide mobile forces, not only those to be used as covering or outpost forces in the initial coastal frontier defense organization, but also the additional forces required to defeat enemy landing or air attacks directed against any part of the coast. When any part of a coastal frontier is threatened, these additional mobile forces will be concentrated with a view to defeating the enemy in the affected area.

6. Relation of Army air forces to coastal frontier defense.--In operations against enemy attacks along our coast and in the waters adjacent thereto, the operations of Army and Navy aviation will overlap to a certain extent. That is, Army aircraft will necessarily have to operate over the sea and Navy aircraft may at times have to operate over the land. In any case, no restrictions will be placed upon the complete freedom of either service to utilize against the enemy the full power of all aircraft available and any and all facilities that may be necessary to make that power effective. Army air forces are a part of the mobile Army forces engaged in the direct defense of the coast. Their functions and operations will be governed by the principles outlined in paragraphs 12, 13, 15, 20, 21, and 22, Joint Action of the Army and the Navy, and the following quoted paragraphs from J.B. No. 349 (Serial No. 539) subject, "Doctrines for the Employment of the GHQ Air Force":

   (b) When any sector of a frontier is threatened, units of all arms, including units of the Air Corps, will be concentrated in support of the covering forces and the operations of all components will be in accordance with the general plan and the specific decisions of the frontier and sector commander. The Army Air Corps operates along the coast under the same conditions as in other operations except that occasions may arise when the GHQ air force or units thereof may act in conjunction with naval air forces under temporary direction of naval commanders; or similarly when naval air forces may operate in conjunction with and under temporary direction of Army commanders.

   (c) The Army is responsible for the direct defense of the coast. This responsibility and the possibility that naval strategy may demand

the presence of the Fleet in another theater require that joint plans for coastal frontier defense be drawn without counting upon the assistance of the Fleet as distinguished form naval local defense forces. But it should be borne in mind that, when the Fleet is so situated that it can and does operate effectively against enemy forces afloat that are approaching some sector of the coast, the security of such sector against major attacks ensured for the time being.

(d) In addition to a radio communication system, the Navy maintains shore stations at strategical centers, where scouting and patrolling seaplanes may be concentrated to meet naval situations. These naval forces are important elements in the communications and information service, and would normally be the source of the first notice of the approach of an enemy by the sea. When the Army GHQ air force operates along the coast, it maintains such reconnaissance as is essential to its combat efficiency. The coordination and cooperation of these two sources of information are secured by joint plans prepared by frontier, sector, overseas department, and naval district authorities. Such plans should provide for augmentation of one service by the other in gaining and disseminating information of enemy movements offshore.

(e) When the Fleet as distinguished from naval local defense forces is strategically present and free to act, paramount interest in operations at sea rests with the Navy. If the GHQ air force joins in such operations, it will be in conjunction with and under the temporary command of the naval commander. In the absence of the Fleet, the primary responsibility of securing information of hostile fleet movements rests with naval district forces supplemented by Army Air Corps units. However, in either situation the GHQ air force retains the responsibility for such reconnaissance as is essential to its combat efficiency.

(f) In the absence of sufficient naval forces to engage the enemy at sea, a major attack upon the coast may develop so as to require the utilization of the GHQ air force in three phases as follows:

1st phase--The conduct of reconnaissance over the sea approaches to the coast and (when favorable opportunity presents itself) the attack of enemy elements.

2nd phase--The support of artillery involving both fixed and mobile guns and mines, by aircraft conducting observation, reconnaissance, and offensive operations, from the time the enemy comes within range of ground weapons, until he is driven off or the operation enters the third phase.

3rd phase--Air operations in connection with the use of all arms on our coastal frontier.

Reconnaissance, as outlined for the first phase, will be continued to the extent possible throughout the later phases.

(g) War plans.--In peace-time planning for war-time use under any of our existing war plans, each coastal frontier plan, and where necessary, each sector and subsector plan will include plans for the employment

of such air units as may be assigned under the particular war plan involved. In the preparation of these plans, consideration will be given to the category of defense as defined in chapter V, part X (sec. III of 1935 revision), Joint Action of the Army and the Navy, and specified in the particular war plan in question. Each specific war plan prepared by the War Department will set forth the initial missions assigned the GHQ air force and, in general terms, the operations to be undertaken. Based upon these missions, the GHQ air force commander will prepare his plan covering the details of concentration, the missions, and the general plan of initial operations to be undertaken by the various elements of the GHQ air force.

(h) Defense projects.--Harbor defense projects will contain a statement of the minimum observation aviation needed for reconnaissance and observation of fire for the harbor defense artillery included in such project.

(i) Installations and facilities.--The most important of these are communications, airdromes, and landing fields. Of the first, the radio systems of the naval districts and of the Coast Guard are available, and joint plans contemplate their utilization in connection with any additional stations found necessary and installed by either service. Harbor defense projects and the plans of coastal frontier commanders will make provision for the airdrome areas and installations and the communications and supply arrangements for the effective operation in war of the air organizations assigned. In addition, the plans of each coastal frontier commander will contemplate and provide, in consultation with the GHQ air force commander, for the possibility of the operation of the entire GHQ air force within the limits of such coastal frontier command, by including in such plans logistical provisions for the entire GHQ air force, should it so operate. Civilian installations and establishments will be utilized to the fullest extent practicable. Where facilities do not exist, all work possible under current appropriations should be done to prepare them so as to permit M-day operation.

(j) In overseas department, the utilization of the aviation component of the garrison will be as directed by the department commander.

7. Naval local defense forces.

   1. The naval local defense forces are furnished by naval districts from such surface, subsurface, and aircraft as may be made available, including small submarines, old destroyers, mine vessels, and aircraft tenders, with such local vessels as are taken over in time of war for naval district use.

   2. The naval local defense forces of a naval district may comprise any or all of the following task forces:

      1. The inshore patrol, which may be composed of section bases, submarine bases, destroyer bases and air

stations; coastal lookout system, including lightships, lighthouses, Coast Guard stations, and special lookout stations; motor boats, submarine chasers, yachts, aircraft, mine sweepers, guard ships, aircraft tenders, and additional task forces in special cases, with the following duties:

1. To execute the Navy's part of all joint plans for defensive coastal areas.

2. To search for, locate, report, and attack enemy vessels operating close in to the coast and off harbor entrances.

3. To sweep such channels close in to the coast and off harbor entrances as are necessary for our naval forces and merchant shipping, and to clear mine fields laid by the enemy.

4. To patrol the outer limits of defensive coastal areas in order to convey to the harbor defense commander prompt and full information of the approach of friendly or hostile vessels, including all those of the offshore patrol. This information is to be conveyed directly to the nearest elements of the Army communication system.

5. To patrol the areas of obstacles, especially during thick weather or darkness, to protect the obstacles, and to prevent light craft from going over them.

6. To operate a system of control including piloting in the defensive sea and defensive coastal areas.

7. To maintain a guard ship at or near harbor entrances to see that all vessels leaving or entering port give the proper recognition and clearance signals and to transmit orders to shipping as directed.

8. To furnish with routing instructions all merchant vessels departing without escort.

9. To maintain a coastal-lookout system along the district coast line by use of the Coast Guard stations and Lighthouse Service, and special lookout stations to prevent communication between persons on shore and the enemy.

10. To maintain, through the Lighthouse Service in the district, the system of buoyage, lights, and other aids to navigation regularly established, with such modifications and changes as military necessity may require.

11. To render prompt assistance to merchant shipping and naval units in case of collision, breakdown, or other accident in port or along the coast.

12. To exercise naval control of harbors through the captain of the port, when the Treasury Department requests the Navy to exercise such control.
2. The offshore patrol, which may be composed of destroyers, submarines, mine sweepers, gunboats, eagle boats, yachts, aircraft tenders, aircraft, and additional types in special cases, with the following duties:

   1. TO patrol systematically the coastal zone outside of those parts assigned to the inshore patrol.

   2. To develop information of, report, and attack enemy forces sighted, in accordance with the doctrine of the patrol.

   3. To supplement and support the main armament gunfire of the harbor defenses.

   4. To lay mine fields and sweep against enemy mines outside the field of operations of the inshore patrol.

3. The escort force, which may be composed of any suitable and available naval forces charged with the duty of protecting convoys within the naval district waters.

4. A coastal force may be organized to operate within the coastal zone. It will be organized from suitable and available naval forces. Such coastal force will be in addition to the forces required for each naval district.

5. In view of the paramount interest of the Army in defensive coastal areas involving existing harbor defenses, the commander of the inshore patrol, who will be stationed ashore, should have his headquarters located as conveniently as possible to the headquarters of the harbor defense commander and at the same location if practicable. In any event he should be in direct communication with the harbor defense commander, as well as in direct connection with all naval activities in the defensive coastal area.
8. Defensive coastal area.

   1. Extent.--Defensive coastal areas will be delimited by joint agreement between the Army and the Navy. Each defensive coastal area will cover that part of the coastal zone and adjacent seacoast which will require an intensive joint defense by reason of the inclusion therein of valuable harbors, stretches of the coast where hostile landings can be made in connection with attacks on our harbors or on industrial trial centers on or near the coast which are subject to attack from the sea. Defensive coastal areas will ordinarily include land and water areas in the vicinity of a fortified harbor, in which will be located in time of peace some personnel and usually a considerable amount of the matériel pertaining to the harbor defenses.

   2. Harbor defenses.

      1. Harbor defenses are highly organized, permanently defended localities within sectors or subsectors of a coastal frontier whose broad mission is to protect important coastal areas (seaports, naval bases, and anchorages) and utilities primarily against attack from the sea. They are an element of the defensive organization of the subsector or sector in which they are located and they operate under subsector or sector control.

2. The defensive elements of harbor defenses consist of the fixed and mobile seacoast artillery, the antiaircraft artillery, searchlights, controlled mines, underwater listening posts, subaqueous sound-ranging system, observation and fire-control system, harbor patrol boats and supporting aircraft with personnel for manning the same.

3. Harbor defenses provide protected anchorages for naval forces and commercial shipping and support their debouchment therefrom.

4. The Army is responsible for the defense against aerial attack of all military and naval facilities ashore within a harbor area.

5. War-time personnel of the Army in these areas will consist essentially of harbor defense troops reinforced by Army air elements. In the usual case mobile troops will be limited to those manning reinforcing mobile artillery, railway and tractor, allotted to seacoast defense. The harbor defense troops themselves will thus have the mission of beach defense in the vicinity of the batteries. A limited number of mobile troops may be assigned to the harbor defense for local beach defense; the further reinforcement of the area by mobile troops will, in general, not take place until the enemy situation indicates an attack in force involving landings and requiring a considerable mobile force for defense against landing attacks.

6. The peace-time matériel consists of seacoast and antiaircraft guns of various calibers, the fire-control establishments for these guns, together with searchlights and with mine structures when the hydrography and current conditions render a controlled mine project feasible.

7. In time of war, other obstacles, such as torpedo-defense nets, antisubmarine nets, booms, built-in obstructions, and contact mines may find employment, primarily in the harbor channel areas, to increase the resistance against enemy penetration into the inner harbor

areas. For the purpose of detecting the presence of enemy underwater vessels or of any vessel during the hours of darkness or in fog or thick weather, a system of underwater listening posts, both fixed and on the vessels assigned to harbor defense activities, may be installed.
8. In the installations and upkeep of obstacles, full use will have to be made of a considerable part of the available local Government-owned and private floating equipment. Where Army and Navy requirements conflict, agreement as to priorities will be reached between the local commanders of the two services and recommendations made to the War and Navy Departments respecting same.

9. The defense will extend its operations to seaward as far as possible by the use of the local defense forces and aircraft of both the Army and the naval local defense forces.
3. Communications.--The system of communication between elements of the Army and the Navy requires most careful consideration because of the intimate relations existing between the elements of both services on land, on the water, and in the air. The system must give consideration to all the forms of communication that may find employment. It is further vitally important that the two services be trained together in time of peace to insure complete understanding of the system. Provision must be made for bringing all incoming information of the enemy by the quickest possible means into the interested headquarters of both the Army and the Navy, and for disseminating such information rapidly and accurately. Reports from elements of the offshore patrol should, as a rule, be sent to the headquarters of both the senior Army and Navy officers in the area. For reports from elements of the inshore patrol, the most direct communication is desirable by all available means from naval elements to batteries, forts, and command posts of the Army. A system of identification signals for all friendly naval craft approaching defensive coastal areas must be established.

4. General.--The Army is responsible for the development, installation, and operation of the equipment of fixed listening posts, of the listening equipment required for defense vessels under its control, and for the immediate transmission of information received by these posts to the Navy units of the defense.
9. [»] Defensive sea areas.

   1. Since the object of establishing defensive sea areas is to control shipping, the proclaiming of such an area obligates the Navy to control shipping therein and puts the burden to enforce this control upon the naval forces. The number and size of defensive sea areas should be reduced to the minimum consistent with security, in order to minimize the burden upon the naval forces, and interference with shipping.

   2. Authority for the establishment of defensive sea areas in vested in the President of the United States by section 44 of the act entitled "An act to codify, revise, and amend the penal laws of the United States, approved March fourth, nineteen hundred and nine", as amended by the act "Making appropriations for the naval service for the fiscal year ending June thirtieth, nineteen hundred and eighteen, and for other purposes", approved March 4, 1917.

   3. When war with a specific power appears probable, the Secretary of the Navy submits recommendations to the President as to the defensive sea areas to be proclaimed and the time when they shall be proclaimed. If and when the development of the war necessitates, he submits subsequent recommendations as to additional defensive sea areas to be proclaimed.

   4. The Secretary of the Navy is charged with the preparation, for the signature of the President, of the proclamation designating defensive sea areas, with their outer definite limits, and with the publication thereof. He is further charged with the preparation and publication of regulations pertaining thereto and with the enforcement of such regulations.

   5. Copies of the local regulations for the guidance of the armed forces issued in time of war by the commandants of naval districts for the defensive sea areas within their districts

will be furnished to harbor defense commanders and other Army authorities concerned.
10. Defense against landing attacks.

    1. Measures and operations demanded of the defense.

       1. Enemy landing operations in force must be opposed to the utmost. To this end the Army forces within the coastal frontier will be augmented by forces from the strategic or general reserve, the Army GHQ air force, and by other available Army forces. The naval local defense forces will be augmented by any other naval forces available. The successful frustration of the hostile landing operation will depend largely upon the timely concentration of the requisite forces at the locality against which the main attack is being directed. It is therefore of vital importance that everything be done to discover the focal point of this main attack at the earliest possible moment. For this reason the defense must initiate the following operations as early as possible:

          1. Location of the hostile force at sea, and maintenance of observation of this force.

          2. Interference with the hostile force as far offshore as practicable to prevent or delay its approach.

          3. Resistance in coastal zone waters and at the shore, taking advantage of the adverse situation in which the attacker is placed just prior to and during landing.

       2. In general, the enemy may be expected to attempt to make landings may be mere feints. The coastline should be carefully studied with a view to determine the places which the enemy is most likely to use for landings, principal or secondary.

    2. Steps in the joint organization and operations against landing attack.--Complete preparation for opposing an enemy landing in force requires the following steps

in correctly organizing and employing all possible means of defense:

1. Organization of a beach defense for important localities.

2. The selection and organization of the principal defensive positions in rear and on the flanks of the portion of the shore line to be defended.

3. Preparation of a complete joint system of signal communications to connect with one another all land, air, and water elements, and to insure intelligence of the enemy getting to the shore posts of command. Organization of an aircraft warning service to warn industrial centers and other important areas of the approach of hostile aircraft.

4. Distant reconnaissance by available air elements and naval vessels of enemy approach in the coastal zone.

5. An air offensive by all available Army and Navy aircraft in order to secure superiority in the air and to destroy at sea the approaching hostile elements that are vital to the enemy in making a successful landing.

6. Employment of the available naval forces to seaward to keep contact with an attack the enemy; patrol of the beach defenses and beach obstacles by the Army with outpost detachments, aircraft, and vessels to give warning of actual landing operations; maintenance of these beach obstacles by vessels of the Army.

7. Bombardment by heavy land-employed artillery and by aircraft to hold hostile vessels at a distance, in order to deny the enemy effective artillery preparation of the landing area and to increase the difficulties of his debarkation and approach to the shore.

8. Determined resistance by the Army to the enemy';s movement in small boats in landing waves to the shore, light and medium artillery fire, together with personnel, bombs and machine-gun fire by aircraft,

being used in support of the troops occupying the strong points of the beach defenses.
9. Resolute resistance at the shore line by troops occupying the first defensive position, coupled with the movement of infantry reserves and artillery, in support of these troops, against the hostile main landing effort as soon as it can be determined.

10. Counterattack by subsector and larger reserves, supported by all available artillery fire, to destroy enemy forces that have landed or, if this be impossible, to confine the enemy's advance to a limited strip along the beach, while continuing the attacks by air and subsurface craft against transports, supply ships, carriers, and small landing boats.
11. Obstacles--types.

    1. General--The term obstacle as herein used includes any object which is placed in the water to interfere with the movement of ships or their torpedoes. Included under this term are nets, booms, piles, sunken ships, and mines. Obstacles are used to close harbor channel areas completely, to bar direct approach to channels, or to force adoption of ship formation and movements unfavorable to the attacker, but favorable to the defense. To be effective, obstacles must be so designed and so well protected that they cannot be removed entirely or destroyed during periods of poor visibility. They are protected by guns capable of delivering rapid fire against the smaller types of craft which the enemy is likely to employ for their removal. Moreover, certain searchlights are located primarily for the illumination of hostile targets in mine fields. Patrol vessels may be needed in the areas containing obstacles during periods of darkness and in thick weather.

    2. Obstructions.--Obstructions such as piles, under water barriers, and sunken vessels are fully effective against all classes of vessels and may be used to help close completely channels or other navigable water areas.

    3. Torpedo-defense nets.-Torpedo-defense nets may be used to close the inner harbor to torpedoes fired from seaward.

4. Antisubmarine nets.--Antisubmarine nets may be used to close the inner harbor area to submarines.

5. Booms.--Booms are used for blocking water areas against the entrance of surface craft.They find application primarily to arrest the movement of ships running at high speed into areas that cannot otherwise be blocked; they may be used in lieu of antisubmarine nets in shallow entrances which submarines cannot enter submerged.

6. Mines.--Mines are of two types: Controlled and contact. The former are provided and installed by the Army; the latter by the Navy. Mines, both controlled and contact, employed in any one defensive coastal area constitute the mine barrier for that area. The barrier may consist of two barrages--an inner, or essentially controlled mine barrage which is an integral part of the fixed defenses of most of our important harbors, and an outer barrage of contact mines.

Section IV
Organization and Command

33. Joint organization and command.--Coastal divisions with geographic coterminous boundaries within which an Army officer and a naval officer will exercise command over the Army forces and the Navy forces, respectively, assigned for the defense of these divisions, have been established in order to provide a joint organization and to ensure the effective coordination of Army and Navy forces employed in coastal frontier defense. These coastal divisions comprise coastal frontiers, sectors, and subsectors. The joint organization, together with the commanders responsible for the execution of security measures on and after M-day and the necessary peace-time planning therefor, are as stated below. (See map attached showing coastal frontiers, sectors, subsectors, and defensive coastal areas.)

34. North Atlantic coastal frontier.

    1. [»] Boundaries.

       Northern.--Northern boundary of the United States.

       Southern.--Diamond Shoal Lightship, Hatteras Inlet, inclusive, southern and western boundary of Dare County (N.C.), Albemarle

Sound, Chowan River, Virginia-North Caroline boundary to the west, all inclusive.
2. Commanders.

   Army.--To be designated in specific war plans. The Commanding General, First Army, is responsible for security measures on M-day and for peace-time planning therefor.

   Navy.--The commandants of the First, Third, Fourth, and Fifth Naval Districts will command the naval forces assigned to their respective districts. They will arrange for the joint tactical employment in cooperation with the Army, in case of emergency, of the naval forces assigned to their districts.

3. Sectors.--The North Atlantic coastal frontier is divided into the following defense sectors:

   1. New England sector.

      1. Boundaries.

         Northern.--Northern boundary of the United States.

         Southern.--Nantucket Shoals Lightship, exclusive; Block Island, inclusive; Rhode Island-Connecticut boundary.

      2. Commanders.

         Army.--First Coast Artillery district commander.

         Navy.--Commandant, First Naval District. This sector is subdivided into the Portland, Boston, and Newport subsectors, with boundaries as follows:

         1. Between the Portland and the Boston subsectors: Northern boundary of Massachusetts.

         2. Between the Boston and the newport subsectors: Pollock Rip Slue Lightship, Monomoy Light, Bishop and Clerks' Light, Cotuit Bay, Bourne, Taunton, northern boundary of Rhode Island, all to Boston subsector.

   2. New York sector.
      Boundaries.

      Northern.--Nantucket Shoals Lightship, inclusive; Block Island, exclusive; Rhode Island-Connecticut boundary.

Southern.--Point Pleasant, Bordentown, both exclusive; Trenton, inclusive.
2. Commanders.

   Army.--Second Coast Artillery district commander.

   Navy.--Commandant, Third Naval District.

3. This sector is subdivided into the Long Island and New Jersey subsectors with boundary as follows:

   Between subsectors: The Sandy Hook Peninsula and lower New York Bay to the Long Island subsector.

3. Delaware-Chesapeake sector.

   1. [»] Boundaries.

      Northern.--Point Pleasant, Bordentown, both inclusive; Trenton, exclusive.

      Southern.--Diamond Shoal Lightship, Hatteras Inlet, inclusive; southern and western boundary of Dare County (N.C.); Albemarle Sound, Chowan River; Virginia-North Carolina boundary to the west, all inclusive. This sector will be subdivided into the Delaware and the Chesapeake subsectors, with the boundary as Winter Quarter Shoal Lightship (to Delaware subsector), southern and western boundary of Delaware.

   2. Commanders.

      Army.--Third Coast Artillery district commander.

      Navy.--The commandants of the Fourth and Fifth Naval Districts will command the naval forces assigned to their respective districts. They will arrange for the joint tactical employment in cooperation with the Army, in case of emergency, of the naval forces assigned to their districts.

35. Southern coastal frontier.

    1. [»] Boundaries.

       Northern.--Diamond Shoal Lightship, Hatteras Inlet, exclusive; southern and western boundary of Dare County (N.C.); Albemarle Sound, Chowan River; Virginia-North Caroline boundary to the west, all exclusive.

       Southern.--The Rio Grande.

2. Commanders.

   Army.--Fourth Coast Artillery district commander. The Commanding General, Third Army, is responsible for coordination of security measures on M-day and of supervision of peace-time planning therefor.

   Navy.--The commandants of the Sixth, Seventh, and Eighth Naval Districts will command the naval forces assigned to their respective districts. They will arrange for the joint tactical employment in cooperation with the Army, in case of emergency, of the naval forces assigned to their districts.

3. Sectors.--This frontier will be subdivided into defense sectors of Carolina, Florida, and Gulf, corresponding territorially to the Sixth, Seventh, and Eight Naval Districts, respectively.
36. Pacific coastal frontier.

    1. Boundaries.

       Northern.--Northern boundary of Washington except that Alaska is part of the Pacific coastal frontier.

       Southern.--Southern boundary of the United States.

    2. Commanders.

       Army.--Ninth Coast Artillery district commander. The Commanding General, Fourth Army, is responsible for coordination of security measures on M-day and of supervision of peace-time planning therefor.

       Navy.--The commandants of the Eleventh, Twelfth, and Thirteenth Naval Districts will command the naval forces assigned to their respective districts within the limits of the Pacific coastal frontier. They will arrange for the joint tactical employment in cooperation with the Army, in case of emergency, of naval forces assigned to their districts.

    3. Sectors.--This frontier will be subdivided into the southern California, northern California, and northwestern sectors, with boundaries based on those of the present naval districts as follows:

       1. Boundary between the southern California and northern California sectors, Santa Maria River.

       2. Boundary between the northern California and the northwestern sectors, northern boundary of California.

4. Sectors of this frontier are further subdivided into subsectors with boundaries as follows:

   1. San Diego subsector: Mexican boundary to San Mateo Point, inclusive.

   2. San Pedro subsector: San Mateo Point, exclusive, to Santa Maria River, exclusive.

   3. Monterey subsectors: Santa Maria River, inclusive, to Pigeon Point, inclusive.

   4. San Francisco subsector: Pigeon Point, exclusive, to northern boundary of California.

   5. Columbia River subsector: Northern boundary of California to Moclips, Wash., inclusive.

   6. Seattle subsector: Moclips, Wash., exclusive, to northern boundary of Washington.
37. The Great Lakes coastal frontier.

    1. Boundaries.--The frontier extends from Isle Royal, mouth of Pigeon River, northern shore of Lake Superior, western boundary of Wisconsin, all inclusive, to mouth of Raquette River, N.Y., exclusive.

    2. Commanders.

       Army.--To be designated in specific war plans. The Commanding General, Second Army, is responsible for security measures on M-day and for peace-time planning therefor.

       Navy.--To be designated in specific wear plans. The commandant, Ninth Naval District, is responsible for coordination of security measures on M-day and for peace-time planning therefor.

    3. Sectors.--The Great Lakes coastal frontier is divided into the following defense sectors:

       1. Michigan sector.

          1. Boundaries.

             Western.--Isle Royal, mouth of Pigeon River, northern shore of Lake Superior, western boundary of Wisconsin, all inclusive.

             Eastern.--Western shore of Lake Erie, southern boundary of Michigan, all inclusive.

          2. Commanders.

             Army.--To be designated in specific war plans.

             Navy.--Commandant, Ninth Naval District.

3. The Michigan sector is subdivided into the Sault Ste. Marie and the Detroit subsectors with boundary between subsectors as follows: Drummond Island, Point Detour, northern shore of Lake Huron, northern and western shores of Lake Michigan (all to Sault Ste. Marine subsector).
2. Erie sector.

   1. Boundaries.

      Western.--Western shore of Lake Erie,southern boundary of Michigan, all exclusive.

      Eastern.--Niagara River, southern shore of Lake Erie, western boundary of New York.

   2. Commanders.

      Army.--To be designated in specific war plans.

      Navy.--Commandant, Ninth Naval District.

3. Buffalo sector.

   1. Boundaries.

      Western.--Niagara River, southern shore of Lake Erie, western boundary of New York.

      Eastern.--Mouth of Raquette River, N.Y., exclusive.

   2. Commanders.

      Army.--To be designated in specific war plans.

      Navy.--Commandant, Ninth Naval District.

38. Defensive coastal areas.--Defensive coastal areas have been delimited at the localities named below. Commanders will fit defensive coastal areas into the sector and subsector organizations in such a manner as to provide for efficient coastal frontier defense. These defensive coastal areas are--

    Portland Portsmouth Boston New Bedford Narragansett Bay Long Island Sound New York (eastern entrance) New York (southern entrance)

    Delaware Bay and River Chesapeake Bay Baltimore Washington Cape Fear River Charleston Savannah River St. Johns River Key West Tampa

Pensacola Mobile Bay Mississippi River Sabine Pass Galveston San Diego Los Angeles San Francisco

Columbia River Puget Sound Cristobal Balboa Honolulu and Pearl Harbors Manila Bay Subic Bay

39. [»] Defensive sea areas.

    1. From a naval viewpoint, and depending upon the specific emergency, defensive sea areas may be important in the approaches to the following water areas:

       Portland Portsmouth Boston Narragansett Bay Long Island Sound New York Bay Delaware Bay Chesapeake Bay Charleston Key West Pensacola Mobile Mississippi River

       Sabine Pass Galveston Puget Sound Columbia River San Francisco San Pedro San Diego Cristobal Balboa Manila Bay Subic Bay Waters surrounding the Hawaiian Islands

    2. Under the joint organization prescribed herein, commandants of naval districts concerned will study the relationship of defensive sea areas to the defensive coastal areas that may be needed and, in the event that additional defensive sea areas will, in their opinion, be required to meet any specific situation, they will include such additional defensive sea areas in their plans.

Section V
Planning

40. Means to facilitate joint planning.

    1. In order to facilitate joint planning, a planning representative will be designated for the Army commander and for the Navy commander

of each coastal division. The planning and development chain of command in both the Army and the Navy will follow the same lines as for combat. In selecting such planning representatives, officers will be selected who are located conveniently to the area to be defended and whose headquarters have the personnel and other facilities necessary for planning.
2. In addition to the above, the local Army and Navy commanders of coastal areas whose headquarters are in the same vicinity will appoint from among their immediately available officer personnel not more than three officers from each service to constitute a local joint planning committee.In cases where superior headquarters are widely separated, more than one joint planning committee may be organized.
41. Collaboration in joint planning.

    1. In the preparation of such joint coastal frontier defense plans as may be required under a joint basic war plan, the following commanders will collaborate:

       	Army	Navy
       (1) North Atlantic coastal frontier.	COmmanding General, First Army, with	Commandant, Third Naval District.
       (2) Southern coastal frontier.	Commanding General, Third Army, or an officer designated by him, with	Commandant, Sixth Naval District.
       (3) Pacific coastal frontier.	Commanding General, Fourth Army, or an officer designated by him, with	Commandant, Twelfth Naval District
       (4) Great Lakes coastal frontier.	Commanding General, Second Army, with	Commandant, Ninth Naval District

    2. The sector defense plans of the New England sector and of the Delaware-Chesapeake sector will be forwarded by the commandants of the First and Fifth Naval Districts, respectively, to the commandant of the Third Naval District and will be formulated to support the North Atlantic coastal frontier defense plans.

3. The subsector or defensive coastal area defense plans of the Delaware subsector or Delaware Bay defensive coastal area will be forwarded by the commandant, Fourth Naval District, to the commandant, Fifth Naval District, and will be formulated to support the Delaware-Chesapeake sector defense plans.

4. The sector defense plans of the Florida sector and of the Gulf sector will be forwarded by the commandants of the Seventh and Eighth Naval Districts, respectively, to the commandant of the Sixth Naval District and will be formulated to support the southern coastal frontier defense plans.

5. The sector defense plans of the southern California sector and of the northwestern sector will be forwarded by the commandants of the Eleventh and Thirteenth Naval Districts, respectively, to the commandant of the Twelfth Naval District and will be formulated to support the Pacific coastal frontier defense plans.

6. The commandant, Ninth Naval District, will confer with the commandants, Third and Fourth Naval Districts, as to the naval means which may be available for defense in the Erie and Buffalo sectors.
42. Details of joint coastal frontier defense plans.

    1. Each specific war plan will provide for the organization of the defense of the land and coastal frontiers and will designate theaters of operations and the task forces to be employed therein. Actual limiting points and boundary lines between coastal divisions will be modified to the extent necessary to meet the needs of the situation assumed for the specific plan. The covering forces and the initial concentrations made for frontier defense in each plan will be based on the protection of probable objectives of enemy attack, the projected offensive operations, and the combined use of Army and Navy forces. A flexible organization of frontiers is required for tactical operations and the boundaries of coastal divisions may be changed in specific war plans or during the progress of operations.

    2. Under the directive of each joint basic war plan and based on the allocation of forces under Army and Navy supporting defense plans, each frontier, sector, and subsector command of the joint organization for coastal frontier defense will develop and will revise annually joint coastal frontier defense plans applicable--

       1. To the defense to be instituted on M-day.

2. To later defense steps, should such be indicated as desirable to insure frontier defense as the war progresses.
3. Joint coastal frontier, joint sector, and joint subsector defense plans (or defensive coastal area plans when joint subsector plans are not required) will, in general, under the specified category of defense, consider what can be done with the means available; these plans may include or refer to a project for a desired development of means which should also be available on the outbreak of war. In the event that other categories have been indicated as probable later steps in coastal frontier defense, these plans should include what can be done with the means of defense then available; they may also include a project for further desired development.

4. Joint coastal frontier, joint sector, and joint subsector (or defensive coastal area) defense plans will be supported by such Army and Navy operating defense plans as may be necessary. Army and Navy supporting operating defense plans will be prepared to support the joint plan of lowest sequence required to be prepared by a joint basic war plan. The joint coastal frontier defense plans will be submitted to both the War and Navy Departments by the commanders under the joint organization for coast defense immediately subordinate to the respective Departments. All joint coastal frontier defense plans will be authenticated by the signatures of the two commanders who submit them. Supporting Army and Navy operating defense plans will be submitted by the commanders who formulate them to their respective next higher commanders within their respective Departments.

5. 1. Joint coastal frontier defense plans for the North Atlantic coastal frontier will be prepared only for situations included under Categories C, D, and E, as indicated under specific war plans. For situations included under Categories A and B, only joint sector plans for this coastal frontier with their supporting plans will be prepared.

   2. I view of the restricted operations contemplated under a Category A or B defense, subsector plans, in general, will not be required for coastal frontiers to which these categories initially apply.

3. The sequence to be followed in the preparation of joint defense plans is as follows:

   1. Joint coastal frontier plan.

   2. Joint sector plan.

   3. Joint subsector plan or joint defensive coastal area plan.

   Generally, the lowest sequence of plans required for the Navy will be that pertaining to a naval district, whether the naval district is a sector or subsector.

6. The plan of higher sequence will contain the directives for the plan of next lower sequence. The lower sequence plan will be formulated to support the plan of next higher sequence.

7. Army and Navy operating defense plans will obtain their directives from the joint plan they are required to support. They will provide the means and organizations and will insure the Army's and/or Navy's effective operation thereunder.

8. [»] Joint coastal frontier and joint sector defense plans will cover the category of defense, the delimitation of areas (including subsector, defense sea and coastal areas included therein), assignment of missions, allocation of Army forces, to include supporting troops, the air and ground antiaircraft defense measures to be instituted, the designation of areas of responsibility, paramount interest and method of command, the details of joint communications and intelligence services to include the censorship and supervision of cables and wire lines in accordance with approved policy, and an aircraft warning service. These plans or their supporting projects will also make provision for the Army airdrome areas and installations necessary in connection therewith and the communication and supply arrangements for the effective operation in war of the Army air organization assigned. In addition, the plans of each Army coastal frontier commander will contemplate and provide for the possibility of the operation of the entire GHQ air force within the limits of his command by including in such plans logistic provisions for the entire GHQ air force, should it so operate; civilian installations and establishments will be utilized to the fullest extent practicable. Where facilities do not exist, all work possible under current appropriations should be done to prepare them so that M-day operation will be possible.

9. Joint plans of the lowest sequence, such as joint subsector or joint defensive coastal area plans, should contain, either in the plans proper, in appendices or annexes thereto, or in supporting plans or projects--so much of the following as is appropriate:

   1. The relationship of the defensive coastal area to the subsector organization and/or of the subsector to the sector organization.

   2. [»] The category of defense and such delimitation of the area as may be necessary for the coordination of the Army and the Navy forces operating in the area, to include areas of responsibility and paramount interest.

   3. The assignment of missions and allocation of Army forces, to include supporting troops or additional forces required for later defense steps.

   4. The relationship of the area to such defensive sea areas as have to been designated for the vicinity, with special reference to methods of keeping the Army informed of movements of all vessels in the coastal zone and the composition, mission, and methods of operation of the offshore patrol.

   5. Such general plan of the forts, batteries, searchlights, underwater listening posts, air installations, and areas of gunfire and illumination as may be necessary to define the areas of Army responsibility for defense and naval assistance to the Army in this defense, including areas available to the enemy from which he can deliver bombardment fire without effective interference from the land armament.

   6. Definite assignment to the Navy of responsibility and tasks for offensive action in such areas as are covered by the fire of the land armament.

   7. General plan of the part of the underwater defense to be prepared or installed, including the character of the mine barrages, nets, booms, built-in obstructions, and other obstacles, their location, priority of installation, definite responsibility of the Army and the Navy for their provision, estimate of time of installation, definite indication of free passages through mines and openings in nets, navigation range installations required and responsibility for their establishment. Decisions as to which service and what commander in

this service shall determine when these elements shall be placed.
8. Allocation to the Army and the Navy of locally procurable means, particularly vessels and material required for the installation and maintenance of the underwater defense, together with an estimate of the availability of such means, the nature of the alteration required, and the probable cost and time involved.

9. Composition, mission, and method of operation of the inshore patrol, with particular reference to method of protection of underwater defense elements and identification of elements of the patrol with land elements of the defense at night and in thick weather, including a definite decision as to the conditions under which doubtful vessels should be fired upon by the armament of fortification.

10. The air, the ground antiaircraft, and the close-in defense measures; the measures for defense against landing attacks to be instituted on M-day and for the later defense steps to be instituted as the war progresses.

11. The details of joint communication and intelligence services and an aircraft warning service. These details for the joint communication and intelligence services to include the location of headquarters of the several commanders, communication nets of both services, with the additional means, both military and commercial, required and the frequencies allotted to Army and Navy radio nets, responsibilities of Army and Navy commanders as to communication, censorship, and supervision of cables and wire lines as prescribed by higher commanders.

12. General method of operation of the inshore patrol in sweeping and mining operations and in conducting and controlling maritime traffic, including designation and location of entrances and exits to defensive sea areas and of guard ships and methods of control of shipping within the harbor.

13. Composition, mission, and method of employment of other naval local defense task groups, in sufficient detail to indicate the character and degree of cooperation required of Army and Navy air units.

14. Definite establishment of factors controlling the passing of paramount interest from the Navy to the Army in the coastal zone adjacent to the area.

15. Detail of at least one liaison officer by name from each service to represent his commander at the headquarters of the other service and such other liaison officers as may be decided upon jointly.
10. A highly important part in each joint defense plan and project, and in the supporting defense plans and projects developed therefrom, is a definite statement of the time of accomplishment of the individual items under the plans and projects. For plans, these statements of times should be for the means and forces actually available and a consideration of the condition of the means and state of training of the forces. For projects, these statements of times should consider both the time of procurement and the time of installation or training after procurement.

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