AVIATION has furnished a powerful weapon for coast defense. It also has made more difficult the problem of coast defense by introducing the possibility of hostile air raids. Everybody knows that aircraft can fly over land and water, and that they can carry bombs that can sink surface craft. This has created an impression that air forces acting alone, without support of the other elements of the Army or Navy, can effectively defend our coasts and protect shipping along our coasts. Some persons have gone so far as to propose that the duty of patrolling the coastal sea lanes be taken away from the Navy and turned over entirely to the Army Air Service. It is unimportant to the people of the United States who does this work so long as it is done well. Herein is the crux of the whole question.
I. Control of Sea Areas
In considering the subject of coast defense it is necessary to visualize the conditions we shall find in actual warfare at sea. To conduct and to control mercantile and military transportation by sea in time of war requires naval power. As long as men and merchandise are transported in ships in the sea—and there is no likelihood that this mode of transportation ever will be superseded—navies will be required to safeguard overseas interests. The great bulk of the world’s maritime trade must always be carried in surface ships, for submarines and aircraft are inherently uneconomical as freight carriers and never can compete successfully with surface ships in oversea commerce. Therefore, the principal task of naval forces—whether submarine, surface, or aerial—is to control the highways on the surface of the sea.
Unless supported by seacraft, aircraft probably never will be able to exercise uninterrupted control over large or remote sea areas. Aircraft and seacraft are both limited as to the time and the distance that they can operate away from a base, but the time that aircraft can remain in the air compared to the time that ships can remain at sea is so short that ships probably will always be the controlling factor in the larger sea areas, with aircraft acting to assist them.
II. Mission of Coast Defense
Coast defense is defense not only against invasion in force from overseas, but against all other forms of hostile coastal activities. It involves protection of shipping, of cities, and of vital communications against attack by sea craft, aircraft, and landing parties. Against all these forms of attack every force that can contribute to the enemy’s defeat should be utilized. Naval forces alone may be sufficient in some cases, army forces alone in other cases, and sometimes it may be necessary to combine both forces to defeat the enemy.
Attacks against coastal areas are of two kinds: major attacks by large forces, and minor attacks or raids by small forces.
It is the duty of the U. S. fleet to intercept on the high seas any large expedition contemplating a descent in force on the coasts, and to engage it before any actual damage can be effected or landing made. If the fleet is defeated the task of repelling invasion falls to the Army. Major attacks of this character will not be discussed, as we are here concerned with the forces established for the specific duty of coast defense.
Minor attacks or raids in the coastal areas by small enemy forces, such as submarines, destroyers, cruisers, and aircraft carriers, cannot always be met by the main fleets and armies, and it is to provide for such contingencies that coast defense forces are required.
The main fleet should not be confined to the duty of defending particular sections of the coast against minor attacks. It should be free to carry out its greater mission of gaining and maintaining control of the sea, which is most effectively accomplished by destroying, neutralizing, or bottling up the enemy’s naval forces. Control of the sea will of itself forestall any invasion in force from overseas and free the mobile army to engage in other missions.
III. Influence of Sea Power
In our last three wars the Navy controlled the seas, and the Army fought in Europe, in Cuba, and in the Philippines. In the Civil War, and the war with Mexico, we had little opposition at sea. The Army was not needed for coast defense, and was able to win the war by defeating the enemy’s armies on their own soil. The Navy prevented supplies reaching the enemy by sea, and was able to transport troops and supplies by sea to the enemy’s ports. But, in the War of 1812, when England was “Mistress of the Seas,” our little Navy and our merchant ships were bottled up at home, save the few ships that escaped the British blockading forces and reached the high sea. Some of these ships succeeded in raids on British shipping. In this war a British squadron landed sailors and soldiers on American soil, marched to Washington, and destroyed the Capitol, White House, and other buildings. The deciding battle of the Revolution, at Yorktown, was won because the French fleet in Chesapeake Bay cut off Cornwallis from the British fleet outside. The daring exploits of Paul Jones in this war illustrate a type of raiding operations which must be guarded against, and the Navy is obligated to take defensive measures against such attacks as well as against the threats of a major force.
IV. Coast Defense Forces
What forces are available for coast defense? Leaving out the main fleet and main army, the forces available for defense are the local defense forces of the Army and Navy. The local coast defense forces of the Navy include surface craft, submarines, and naval aircraft, armed with guns, mines, bombs, and torpedoes. The surface craft include destroyers, mine sweepers, tugs, salvage vessels, sub-chasers, and small patrol craft. Other elements of the Navy in coastal areas are: the industrial establishments for the maintenance, repair and supply of the naval forces; the communication system including radio and radio compass stations; the intelligence system, including the life saving and lighthouse services, and detachments of marines.
The army coast defense forces are composed of the various arms of the Army, the fixed and mobile artillery, including railway and tractor-drawn heavy artillery, searchlights, anti-aircraft guns, army aircraft, the mine planters for laying observation mine fields, and fixed obstructions.
V. Capabilities of Naval Types in Coast Defense
Let us now examine the capabilities of the various types of naval craft for coast defense.
Aircraft.—The development of bombing has given to aircraft great offensive qualities against sea and land forces. Aircraft provide the best defense against other aircraft. The high speed and great range of vision of aircraft make them particularly valuable for scouting. They are superior to seacraft for searching out a given area in a minimum time. Seacraft are better adapted for maintaining a continuous patrol in areas distant from a base, because they can patrol day and night, in fair and foul weather, for a long time without returning to their base for fuel. Airplanes cannot do this unless based on sea craft; they must fly from their shore bases out to the scouting area, and return to their shore bases daily for fuel. Flying back and forth from the base consumes a large amount of fuel and reduces the number of hours available for scouting and patrolling the area. The wear and tear on engines and planes is considerable, and if the patrol is to be maintained indefinitely over an extensive line, large reserves of planes and engines for replacement are required.
Carriers. By using aircraft carriers as bases, the scouting area for airplanes can be extended seaward, but it must be remembered that aviators will experience greater difficulties in operating continuously from carriers at sea, and locating them when returning from a scouting mission than when returning from a scouting mission to an air base ashore. An aircraft carrier while on her station in a patrol area would be subject to submarine and possibly surface attacks.
Submarines. Submarines are especially valuable for patrol and scouting duty, and are excellent either for offensive or defensive work. They can operate independently and continuously in distant areas without supporting forces, for long periods of time, and they are less liable to be seen or destroyed by hostile forces than any other type of patrol craft, but they have the disadvantage of slow speed, and limited vision.
Airships.—Rigid airships possess some, though not all, of the advantages of aircraft and seacraft for scouting and patrol duty. Like airplanes, they have extensive vision and great speed. Like ships, they can slow down, stop, and even back, and have an extensive operating range. But, though vulnerable to gunfire they may, by keeping out of gun range, pierce a screen of hostile surface vessels which surface scouts themselves might be unable to pierce. Although they can easily keep out of range of surface craft, they cannot outrun or outclimb the airplane, but may carry airplanes to a limited extent for protection. They have no great offensive value in sea warfare, and are less reliable as operating units than seacraft. Under favorable conditions they can cover larger areas in a given time than seacraft, and can supplement light cruisers to a certain extent for scouting, but not for screening duty.
VI. Coordination of Types
Each type, submarine, surface vessels, airplane, aircraft carrier, and airship, has advantages and disadvantages peculiar to itself. A skillful naval commander will carefully consider every available type of craft in organizing his forces and in planning their work. He will use each type to the best advantage, assigning each unit to the task that it is best fitted to perform and coordinating the efforts of all to accomplish most effectively the mission of the whole organization. Such an organization composed of different units is like the human body which is composed of different members, each performing its allotted task, all directed by one mind. In a scouting or patrol force each unit is an eye that watches over its allotted sector, and instantly communicates by radio—the Navy’s nerve system—what it sees to the mind of the organization, and, at the direction of this mind, force is applied most effectively. Only such an organization can effectively perform the manifold duties connected with high sea scouting and coastal patrol.
VII. Character of Coastal Operations
The operations necessary for coast defense are of two kinds: precautionary measures and counter attacks. Precautionary measures include scouting and patrolling, escorting and convoying, mine sweeping and mine laying, and operations of the intelligence and communication systems. Counter attacks are those operations designed to repulse the enemy attack when it is developed by the precautionary measures. Both functions require combination of forces to accomplish best results.
VIII. Scouting and Patrolling
An enemy's best chance of success lies in surprise attacks. To prevent surprise by the enemy he must be discovered far enough away from our coast to give sufficient time to our forces to concentrate, intercept, and attack him. The farther away the enemy is discovered the greater time our forces will have to concentrate and attack him. The Navy’s far flung scouting forces at sea afford the best means of locating him at the earliest moment. After locating him they should maintain contact with him and continually report the position, strength, and disposition of his forces. While the enemy approaches the coast our forces can concentrate and advance to meet him under the most favorable conditions. For scouting and patrolling in the coastal areas the Navy uses aircraft, both lighter-than-air and heavier-than-air, surface craft and, submarines. They are based on naval coastal shore bases, which are also used for fitting out, repair, replacement, supply, and mobilization of material and personnel, and on mobile tenders operating along the coast. They are disposed in such manner as to cover given areas most effectively and permit the maximum concentration of force on the enemy in minimum time.
The nationality and character of shipping encountered in the coastal areas must be ascertained by patrol craft. To do this they must exercise the right of search, and therefore must be surface vessels. How can the duty of visiting and searching vessels for contraband be performed by aircraft unassisted by surface vessels? A seaplane may land on the water in fair weather close to the vessel and send a man on board. The Germans, in the last war, tried this with their submarines. It worked well at first. But later, when guns were mounted on merchant ships, and were turned with deadly effect on the submarines, they were forced to abandon the practice of searching vessels at sea. The submarines retaliated by firing torpedoes and sinking ships on sight, remaining submerged without danger to themselves until the ships had been sunk. This violated international law and practice. A seaplane on the water would be helpless if exposed to gunfire from a ship. To avoid danger to themselves pilots of airplanes, if they wished to do so, could bomb merchant vessels on sight, whether prohibited by international law or not. Such practices by any country would force it into the same situation with respect to neutrals in which Germany found herself when her submarines began sinking neutral ships without warning. An airplane could drop a note on the ship or give her radio or visual signal instructions to proceed to a designated port for examination, but it would be impracticable for the airplane to escort the ship into port to insure that the instructions were carried out.
For detecting the presence of submarines certain classes of vessels of the coast defense forces are equipped with listening devices. These “hear” the sounds made by submarines running submerged and it is possible to locate the submarines when the “hunting squadrons” equipped with these devices are skillfully handled. Submarines also use listening devices in their work against surface craft and other submarines. Combination of all types of naval forces is necessary for the most effective scouting and patrolling of sea areas.
IX. Escorting and Convoying
If we are to safeguard our own shipping where it is subject to repeated attack we must protect it with escorts. Consider a twelve knot convoy escorted by airplanes. These have a cruising speed of say ninety miles an hour and a flying radius of a thousand miles. Assume that they can remain in the air twelve hours. They will have to leave the convoy after about ten hours of escort duty in order to return to their bases before running out of fuel. This would furnish a twelve knot convoy with an airplane escort for about 120 miles beyond the shore line. To escort further by airplanes would require a relief escort. In thick weather, the airplane might lose sight of the convoy and would then fail to afford it protection. At night when the convoy was running without lights, as would be necessary in time of war, the same thing might happen. If one of the ships of the convoy were torpedoed she could not be salvaged or towed back to port by airplanes. She might sink, as often happened in the last war, but airplanes could not rescue the passengers.
This all means that surface ships are absolutely essential for the efficient performance of patrol and convoy duty at sea both inshore and offshore, and that means a navy—a navy like the United States Navy with its own aircraft. The need for the latter in addition to ships, is shown below.
We know that during the World War the Navy, in cooperation with the allied navies, kept open our sea communications and effectually intercepted the sea communications of the enemy powers. During this period, while the Navy was escorting and convoying over two million army troops and all of their supplies overseas, the Navy played a most important part in “winning the war.” The air forces of the United States Navy flew over two and one half million miles, patrolling the seas from the various coastal air stations in the United States, England, Ireland, France, Italy, and Canada. Four hundred of our naval airplanes were engaged in this work abroad while the army air forces were being carried overseas or fighting on the western front. Thirty-seven enemy submarines were attacked by naval aircraft. These naval aircraft were working in cooperation with hundreds of surface ships and submarines, all of which were commanded by and operated under the immediate orders of naval officers in accordance with a definite joint plan. Aircraft surface vessels, and submarines were mutually helpful, and the best results were obtained by a combination of all types.
Let us see how these operations were carried out. Take a convoy assembling in one of our great harbors, and suppose that enemy submarines and raiders may be actively operating in that vicinity.
The naval commander of the coastal areas is the officer appointed to direct and coordinate the work of the naval coastal defense forces, which include all types of naval craft, surface, submarine, and air. He is charged with the responsibility of assembling the convoy. He must furnish it with radio and signal instructions and sailing directions, must provide the necessary naval escorts, including naval aircraft, and must assure himself that the coastal waters through which the convoy is to pass are clear of mines and enemy craft.
The convoy is assembled; the orders to the commanding officers have been given; the course, speed, formations to be taken within and without the coastal areas have been made known to the commanders of all units, merchant and naval, engaged in the operation. All is secure inside the anchorage. The convoy and escorting vessels are ready to sail. Outside the anchorage naval aircraft and other naval units have been scouting over the area through which the convoy will pass to drive clear any hostile surface craft or submarines. Other naval aircraft are flying over the channel to see if they can locate any enemy mines, and the mine sweepers are at work in the channel. The naval district commandant, in touch by radio and telephone with all of his units, knows exactly what is going on outside of the harbor. He receives reports as to when the channels have been swept clear, and knows when it is safe to move the convoy.
The harbor defense net is opened to permit the convoy to pass out, and the convoy gets underway. The van of the coastal escort, consisting of sub-chasers and other vessels, precedes the convoy out of the harbor and takes station ahead and on the flanks of the convoy column as the ships in pre-determined order pass down the swept channel. They steam out to sea, and as they reach the open water they deploy to their designated positions in the formation to be maintained during the voyage and commence zigzagging as prescribed in their instructions. The smaller vessels and aircraft of the escort that have been safeguarding the convoy through the narrow waters now begin to leave the convoy to return to their base, while the destroyers and larger vessels of the escort continue with the convoy until relieved by the high sea escort.
The responsibility of the naval district commandant, who has been in charge of all these arrangements, ends only when the coastal escort has safely turned over the convoy to the commander of the high sea escort, who becomes responsible for insuring the safe passage of the convoy over the sea. The fleet will have disposed units strategically to safeguard further this and other convoys in their transoceanic voyages.
Meantime, other convoys, and shipping, are approaching the coast. Their movements are made known to the naval headquarters in the district through the naval communications service, and the same provision must be made for the safety of incoming vessels as was made for the safety of the outgoing convoy just described. These great arteries of sea commerce must be protected by the Navy day and night throughout the war.
During the last war, when the submarine campaign was so active along the coasts of our allies, the allied convoys on approaching the war zone were met far out at sea by properly organized and instructed escorts of naval vessels, which automatically carried the convoy on to the coastal areas, all under the control of naval officers. As they approached the coast they were met by other types of naval craft, including naval aircraft, which continued to safeguard the convoy through the narrow submarine-infested waters. These convoys were made up of ships from all parts of the world, flying the flags of the allied nations. There were fast troop convoys bound for the coast of France. There were convoys of food and munition ships, of moderate speed, supplying the fleet in the north of Scotland and the armies on the western front. There was a continuous flow of small and large convoys bound for the channel ports and the Mediterranean, carrying valuable cargoes of food stuffs and merchandise for the millions toiling in the factories behind the allied lines. Provision had to be made by the Navy for continually safeguarding this incessant flow of shipping, outbound and inbound, from shore line to shore line. The elaborate organization to maintain the necessary escorts of the proper type, to provide them at the proper time and place, and to collect and disseminate the information necessary to coordinate all work was completely under the control of the naval service. The success with which the Navy carried out these duties during the last war was due solely to the fact that the Navy is organized, trained and equipped for this kind of work. It can be said, without exaggeration, that the organization and discipline of the convoys and escorts was as nearly perfect as it is humanly possible for any organization to be. Here, again, we see the combination of air and sea forces.
X. Mine Laying and Mine Sweeping
Mining operations are important in coast defense because all classes of ships are vulnerable to mines. Many vessels, including battleships, submarines and merchant vessels, were destroyed by them in the last war. Channels must be swept clear of mines in the shipping lanes to insure the safe passage of vessels. Mine layers acting on the offensive lay mines off the enemy’s coast, and when on the defensive lay mines to protect given areas off our own coast. An American mine squadron laid a mine barrage of over 50,000 mines in the North Sea during the last war, and cleared the barrage by sweeping up the mines at the end of the war. Mines may be laid by surface craft and by submarines equipped for the purpose. It would be possible for an airplane to lay a mine, but neither submarines nor aircraft are capable of sweeping up mines. All this work must be under the direction of the naval commander who must coordinate all activities of the coast defense forces to insure the safety of shipping.
XI. Intelligence and Communication System
In all military operations, in every theater of action—on the land, at sea, and in the air—accurate and timely information concerning enemy movements is essential to success. The service of information at sea is maintained by the naval scouting and patrol forces which are inseparable from the organization they serve—the Navy. The contacts of all these forces with the naval commander-in-chief must be direct, accurate, and swift. The information must be guarded and flow uninterruptedly to the directing centers of operations ashore and afloat where it is analyzed, acted upon and despatched to all forces having need of it. All units of the fleet and naval coast defense forces are integral parts of the naval communication organization. This organization includes also the naval radio stations on shore, the radio direction finders for locating enemy vessels, and the coastal signal service.
XII. Counter Attacks
If an attack develops after the precautionary measures have been taken, it should be met by counter attack. The strong arm for counter attack at sea is the main fleet, but to meet attacks by seacraft or by aircraft within gun range or within flying range of the coast, there are available the naval coast defense forces, and the aircraft and artillery of the Army. Beyond flying range of the coast, only naval forces would be available. For counter attacks against surface vessels, guns, torpedoes, mines, and aerial bombs may be used. In addition, the depth bomb would be used against submarines, but for counter attacks against aircraft the machine gun carried in aircraft is the most effective weapon.
Picture a situation in which an overseas enemy plans an aircraft attack upon one of our principal cities. He must transport his aircraft across the sea in ships to some point within flying range of the objective before he can launch the attack. The attacking airplanes will have to operate from aircraft carriers or from suitable shore bases in his possession. While the enemy is at sea, and until his ships have reached the point of attack, the problem is distinctly a naval one.
The Navy may prevent the enemy from bringing his aircraft carriers to a favorable point, or may prevent him from establishing a shore base within flying range of the coast. But, once the enemy aircraft have taken the air to attack our cities, only our own aircraft can intercept and defeat them. Fast combat planes are necessary to intercept and defeat the enemy bombers and combat planes accompanying them. The attacking aircraft have an initial advantage difficult to overcome because they can choose their time and their objective, take advantage of weather or darkness to insure surprise, and reach the desired ceiling before the defending planes ca ndo so. Naval aircraft of the coast defense forces consist principally of patrolling, scouting, torpedo and bombing planes, designed principally for use against aircraft, and are not intended primarily for use against air attacks. Against air attacks of this kind, which by whatever means have avoided our fleet, we rely entirely upon the army pursuit planes which are provided for this purpose. The Navy does not maintain pursuit planes on shore bases or stations other than for training purposes. The Army Air Service has the responsibility of meeting attacks of this kind and should be adequately equipped for the purpose. Our main reliance against air attacks of this kind is in the greater number of army pursuit planes available.
XIII. Unity of Command
For coast defense the Navy is the first line, and the Army is the second line. If the first line falls back upon the coast the two lines merge into one. It is generally recognized that when these lines merge, or whenever there is joint action between the Army and Navy, there should be unity of command, but it is not always clear exactly what is meant by unity of command. Some persons unfamiliar with the many activities connected with coast defense believe that all coast defense should be placed under control of the Army. Others believe that all such activities should be placed under the Navy, because coast defense activities are mostly naval.
History abounds in striking illustrations where violation of the principle of unity of command has resulted disastrously. The difficulties of coordinating operations of joint forces—particularly in coast defense—would be greatly increased if, instead of having to coordinate the two existing organizations of the Army and Navy, it were necessary to coordinate with them a third independent organization, as would be the case if there were a separate air force.
Unity of command of joint forces should be directed command which is only general in character. The commander states in general what is to be done, but does not say how it is to be done. The commands of the separate task forces are absolute, the commanders specifying in detail both what is to be done, and how it is to be done. There should be no conflict between the two kinds of command. There will be none if the primary functions of the army and navy forces are adhered to. When forces are joined for a combined operation to accomplish a definite objective, maximum results can be secured only by cooperation and coordination. The Joint Army and Navy Board has laid down the guiding principles to be followed by the Army and Navy to provide unity of command in joint operations in coast defense. Under ordinary circumstances, if the operation is primarily naval the supreme command should be naval. If the operation is primarily military, the Army should command. The same principle should apply to the lesser commands in minor or local operations in which the objectives are subordinate to the main objective.
In the United States both the Army and Navy have functions in coast defense, but the control is not wholly in the hands of either. In Europe the system differs from ours. The coast defense of France is entirely under the Navy until the actual landing of hostile forces takes place. In England it has been a naval function heretofore, all under the control of the naval officer commanding the coast defense forces. Since the formation of the Royal Air Force, where naval aviation and army aviation have been consolidated into an independent organization, the exact status of the Army, Navy and the Air Force with respect to coast defense seems to be indefinite. In Germany coast defense was all under the Navy.
Operations in coastal areas are primarily naval, but the commander of naval coast defense forces should always keep the commander of the army forces advised regarding the development of any situation at sea in which the Army subsequently may be called upon to take part, directly or indirectly.
Should the naval commander request the assistance of the army forces to repel an attack he should advise the army commander as to the situation. He should specify what forces are desired, when and where they will be needed, and the objective. The forces should be furnished if available, and should be directed to report to the naval commander for operation under his direction in cooperation with the naval forces. If an enemy force is greatly superior to the naval force available for use against it, and the naval force is unable to cope with the situation, the naval commander should so notify the army commander. The Army would then have the paramount interest. The naval forces should be turned over to the Army and the joint forces should operate under the direction of the army commander.
XIV. Conclusions
Until airplanes, loaded with bombs, can fly back and forth with impunity across the Atlantic or Pacific Oceans, as they can now do across the English Channel and other inland seas, the problem of coast defense against hostile air raids will remain a much simpler one for the United States than it is for European powers.
A strong navy, composed of all types of craft—submarine, air and surface craft, balanced in numbers, and coordinated in action to insure mutual support, provides the most effective means of repelling overseas attacks and of protecting shipping on the seas. A navy that is strong enough to protect shipping on the high seas certainly can effectively control it along the home coast lines.
If we were to assign exclusively to the Army Air Service the duty of protecting the coastal sea lanes within flying radius of the shore bases, it would still be necessary for the Navy to protect the sea lanes beyond the range of aircraft. There would have to be an imaginary boundary line on the surface of the sea, on one side of which the Army, and on the other side of which the Navy would be responsible. The bordering area would probably develop into a “no man’s sea” over which neither service would claim responsibility. Aircraft, unsupported by seacraft, could never perform efficiently the work required of a naval coast defense force in time of war, no matter how great their flying range. The natural line of demarkation is the shore line, and the natural service for work beyond this line is the Navy. Our Navy, with its aircraft, its submarines and surface vessels of all types, and its complete intelligence and communication system, is amalgamated into an efficient and well balanced organization to do all work from shore line to shore line. The Army Air Service is by nature incapable of doing the Navy’s work.
When submarines were first introduced in our Navy there was some discussion as to whether they should be placed under the Army or under the Navy. Now aviation has become an important and integral arm of the Army and of the Navy. It has supplemented other weapons of both services, but has not supplanted any of them. It has not changed the relation between the Army and the Navy. The Navy has its duties in connection with coast defense which are naval in character, and the Army has its own characteristic duties.
To restrict the Navy in the choice of its weapons or in the facilities for operating them would deprive the Navy of the full play of its power to meet all of its responsibilities. To turn over coastal patrol, or the control of shipping in our coastal sea lanes, now a responsibility of the Navy, to the Army Air Service would duplicate existing functions of the Navy, would confuse the entire problem of coast defense, and would weaken army aviation by diverting it from other important missions.