Foregoing chapters have discussed the antisubmarine aspects of World War II in some detail, both as a history and as an object lesson in rational naval tactics. This would not have been done if it were not feared that a future war might at some time present similar problems. Yet the nature of any hypothetical future submarine and antisubmarine operations is now so uncertain that any discussion of them is highly speculative in character.
It is evident that this volume on antisubmarine warfare has been essentially historical in nature. It has retailed facts and figures from experience collected in the 6 years prior to V-J Day and developed theories to explain and interpret them. Its basis is therefore a dual one, the characteristics and tactics of the German U-boat on the one hand, and those of Allied antisubmarine craft on the other. Had the contestants been different ones, the course of the war would have been altered correspondingly.
The outstanding characteristics typical of the German U-boat throughout most of World War 11 were related to the policy of surfaced operation. Their offensive tactics were predicated on the use of visual detection and tracking on the surface with high speed and maneuverability. Diving was resorted to only in emergency to escape detection or attack. The large wolf packs formed against North Atlantic convoys were characteristic of their emphasis on coordination. Their consequent heavy radio traffic provided important information to the Allies, and their weakness in radar detection techniques gave the Allies a telling advantage against the surfaced U-boat.
On the Allies' side, the overriding importance of maintaining North Atlantic convoys to Britain did more than anything else to determine the general course of the antisubmarine war. This was the central battle, with a great variety of diversionary forays and skirmishes spread over the remainder of the oceans. To defeat the U-boats, their weak points were exploited to the full, especially by radio direction finding position estimates and effective use of radar, both surface and airborne.
The picture would no doubt be different in any future war, for many important changes were in progress during the closing period of World War II. These trends are the most obvious indication of what may be expected in the future.
After the defeat of the U-boats in the summer of 1943, the Germans initiated an extensive program of research and development on methods of U-boat warfare. The high-submerged-speed submarine was probably the most striking result. The ultimate objective was a submarine with turbine propulsion, burning fuel oil with hydrogen peroxide as an oxygen source (the Walter turbine). This was to be the Type XXVI U-boat with a maximum submerged speed of 25 knots for 6 hours instead of 8 knots for 1 hour like the standard type of U-boat. The tactical value of such a speed in attacking convoys and in avoiding search and counterattack would obviously be very considerable. Although the feasibility of Walter turbine propulsion had already been demonstrated at that time, no Type XXVI U-boats were ever built because of production difficulties.57 Several smaller boats, Type XVII, were built, however, for experimental purposes, and trials were in progress by V-E Day.
Less spectacular than the turbine drive U-boat was the high-speed electric drive Type XXI. They were highly streamlined boats with powerful electric motors and high-capacity batteries. The resulting capabilities were a top speed of 15-18 knots submerged for a brief period, and of 10 knots submerged for about 10 hours. U-boat construction was concentrated on the Type XXI during 1944 and considerable numbers of them were ready to start operations in May 1945. No war patrols had actually been made, however.
Both of these types were, of course, to be fitted with Schnorchel, which should also be classified as a post1943 innovation. The idea was not a new one, but its widespread introduction in the summer of 1944 drastically changed the complexion of the antisubmarine war, as was pointed out in previous discussion. Schnorchel must certainly be reckoned with in estimating future trends, and future Schnorchels, equipped with radar camouflage, may be expected to be even more effective than those which the Germans used.
Significant changes were being made at the end of World War II not only in submarine design, but also in weapons for submarine use. The acoustic torpedo discussed in Chapter 15 is the most familiar example,
but there were other developments as well. Long-range and zigzag torpedoes were introduced for use against convoys, considerably increasing the probability of hit. Fortunately few U-boats had opportunities to fire them. The Ingolene torpedo, with the Walter turbine propulsion giving long range and high speed, was developed but not put into operational use. Such weapons may be expected to increase the potential effectiveness of submarines in the future.
On the Allied side end-of-war developments were mostly of the nature of improvements to existing craft and weapons, since they were operating with good success. New types of sonar for improved detection and attack were under consideration, in particular scanning sonar which gave an instantaneous plan position indicator plot of target position. More effective attack weapons were under development, and the recently introduced Squid gave evidence of having a probability of success in attacks about ten times that of ordinary depth charges.
Certain more general developments will also undoubtedly have profound effects on future antisubmarine warfare, just as sonar, radar, and the aircraft profoundly affected it during World War II. Atomic explosives and power utilizing nuclear energy come immediately to mind as the most revolutionary of recent introductions. It is impossible to estimate the effects of such developments now; all that can be done is to point out that they are likely to be considerable. Somewhat less striking, but also of great importance, are the very extensive developments of guided missiles. Homing torpedoes may be considered as a particular class of weapons of this type.
What, then, are we to conclude that the future of submarine and antisubmarine operations will be like. Some conclusion is in order even though we recognize that it can only be a wildly speculative one.
The whole state of naval warfare in the future is uncertain, but it can surely be agreed that control of the sea, including the depths beneath the surface and the space above it, is of prime military importance, and such control may rightly be considered as the objective of naval power. How such control may best be accomplished is a question for future analysis and planning to decide. The general means available are naval craft and missiles; for modern warfare, no longer a matter of personal combat, is based on the missile, the means of implanting a destructive agent in the enemy's midst from long range. Naval craft - ships, aircraft, and submarines - are fundamentally missile-carriers whose aim is to launch missiles so that they reach the proper place.
The characteristics of each type of craft are determined in part by the requirements of the missile which it launches. In part, however, they are intrinsic - speed, endurance, and maneuverability. Relative ease of detecting the enemy and being detected by him are also of great importance.
In the past submarines have been built around the torpedo as missile. Improvements in torpedo design and the possible introduction of submarine-launched guided missiles may significantly alter its role in the future. The great intrinsic advantage of the submarine is its invisibility, in which it still exceeds all other types of craft. Means for overcoming this invisibility are likely to remain the chief concern of antisubmarine measures. Their detailed nature must, however, be determined in terms of the use to which submarines are put and of the type of submarines involved.
A satisfactory estimate of the most probable enemy use of submarines can hardly be made without first deciding on the general tactical and strategical situation which is likely to exist. We should first determine who will be fighting whom, what bases and facilities each will have, what supply lines or other objectives are open to enemy submarine attack. Setting up such a complete problem is, however, beyond the scope of this discussion, but we can still make some predictions in general terms.
In the first place it is reasonable to expect that submarine tactics which proved to be highly effective in World War II will be tried again in the future. In particular the use of submarines to attack merchant shipping is likely to be repeated by our enemies so long as our strategy is dependent on such ships. In any major war this is likely to be the case, since we will use ships to supply bases outside the continental United States and to import necessary materials of war. Only if the enemy expected to win such a rapid and crushing victory as to make destruction of our shipping unnecessary would he be expected to ignore the importance of a submarine campaign against merchant ships.
The developments of the last period of World War II support this point of view. The new types of German U-boats which were designed and constructed after 1943 were intended for the same basic purpose as the earlier ones-to attack merchant ships. No
major change was envisaged, but it was hoped that the increased U-boat speed would restore their tactical advantage and permit them to resume effective attacks against convoys, even when operating submerged to gain safety from aircraft.
The use of submarines for anti-shipping operations involves use of the torpedo as the primary weapon. New developments suggest, however, that different weapons, such as a guided missile of the V-bomb type, might also be launched from submarines. If such a missile were designed to carry nuclear explosives, the destructive power of the weapons which even a relatively small submarine could carry would be many times greater than that of a battleship or carrier at present. Weapons might well be launched with accuracy comparable to that of present gunnery or bombing. Since the submarine is an all-but-invisible craft, developments of this sort might be expected to be extremely effective.
The detailed evaluation of the effectiveness of possible types of future submarine operations is beyond the scope of this discussion and could not be made now in any case. It is first necessary to determine the fundamental capabilities of the craft and missiles that may be involved, with all possible new developments and improvements. When this has been done the tactical evaluation can be undertaken.
It does appear, however, that future developments are not likely to eliminate the submarine's great merit, its relative invisibility. At the same time the striking power of submarines is likely to increase. We may safely conclude that submarine and antisubmarine warfare will be highly important phases of any future naval conflict.
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