The effectiveness of merchant ships in ocean transport-and of surface naval vessels to protect them or to blockade them as the circumstances require- was the foundation on which Great Britain built her empire, on which the United States bases the credibility of her international commitments and by which the U.S.S.R. hopes to expand her role in Africa and Asia. That foundation continues to erode under an irresistible tide of technology, the key expressions of which are the submarine and the missile.

To many this is an unbelievable assertion, doubly so because its consequences for international relations as they are currently constituted are so massive and, in general, so detrimental. The skeptics, who know from experience that most evaluations of the future occur more slowly than claimed, or not at all, are inclined to wait for results. In this case results could best come from the test of battle. And if the balance between the various forces which are deployed on the oceans lies elsewhere than where "tradition" (an increasingly sometime thing) has placed it, the resulting surprises could lead to ill-considered remedies. These could be as divergent as surrender of a major goal, or nuclear war-if the latter is a remedy. Thus, an understanding of the various technical changes which have occurred since the launching of the Nautilus is inescapable if the planning of foreign policy, and of naval building programs, is to be realistic.

That large surface vessels-merchant as well as naval-will no longer survive the onslaught of the submarines, surveillance systems, homing weapons, and the rest of the paraphernalia of twentieth-century military technology is a proposition with a massive precedent: the fate of the battleship. Who, among the official hierarchies of both Allied and Axis fleets, believed before the fact that this supreme symbol of naval power would perish because it was not, to the same degree as its enemies, a creature of the new technology?

As if the technical issues were not in themselves sufficiently complicated, their interpretation in a particular theater can be radically modified by geographic and political aspects. In a narrow sea like the Mediterranean, for example, surface fleets may have to deal with submarines, shore-based aircraft, and perhaps with a revived and longer-range form of coast artillery-surface-to-surface missiles. Yet, if a naval contest were to occur in that sea, the most important factor might be the Turkish position on traffic through the Dardanelles. That is why it is clearer to discuss the problem in a narrower framework-the shifting balance between large surface ships and submarines.

As the years go on, the likelihood strengthens that, in spite of the most strenuous anti-submarine efforts carried on with the most exotic of available equipment, a submarine fleet of relatively moderate size-perhaps several hundred vessels-can destroy or drive into port any present-day surface navy and merchant fleet. That does not necessarily mean our submarine fleet, for it is armed primarily with anti-submarine weapons. Not all submarine navies, though, design for our hierarchy of missions.

Admitting that the contingency described here is within the bounds of military technology, can we comfort ourselves with the illusion that such a maritime disaster could be fended off by threatening a resort to nuclear war? When those nations which can deploy large submarine fleets also possess nuclear warheads and the missiles to carry them, whom can we threaten? If the stakes are less than total, if they involve, in some distant corner of the world, a blow to our pride or a loss to our pocketbook, will we not be forced to the same restraint we have shown in Korea and Vietnam? The threat of nuclear war could be invoked with limited danger to us when a grossly unequal balance existed between American and foreign nuclear power. It was the basis of the sanctuary in which our naval forces largely operated during the Korean and Vietnam conflicts. This sanctuary has of course been to our enormous benefit, but it has also served to confuse us with a false sense of omnipotence at sea.

Today only one nation has in being a submarine fleet of sufficient size to be a major threat. However, as other claimants to world influence expand their operations, they will inevitably discover, if they do not already know, that submarines are a key element in their power base. And submarines, even nuclear submarines, are not all that difficult to build in quantity. Germany built about 1,100 full-sized diesel-electric submarines, in addition to hundreds of one- and two-man submarines, during World War II. Not until near the end of the war did she begin to utilize fully the then available mass production techniques. Although nuclear attack submarines, in their current stage of design, average several times the weight of a diesel-electric, there is no material or technical reason to prevent a major industrial nation from building scores of them per year. Pound for pound, submarines place less stress on a country's production capabilities than do airplanes. Such treaties as today control the tonnage and quantity of submarine fleets are of the moment, not for eternity.

Technology continues to demonstrate its universal availability. The means to obtain U-235 and plutonium become cheaper and more widespread by the year, and so do the means to deliver the warheads. Red China is detonating its nuclear bombs and launching its satellites on a schedule our own intelligence has predicted. Russia has become a nuclear power on a scale as vast as that of the United States. France has exploded its fusion bombs to an audience of submarines from several nations. Like Britain, she has demonstrated her ability to construct nuclear power plants. Japan and Germany are building excellent diesel-electric submarines and have each constructed a nuclear-powered ship. Both have the capability, should they care to exercise it, to construct nuclear-armed missiles. In another decade there should be at least half-a-dozen countries capable of maintaining both an effective submarine force and a nuclear capability.

In that era, suppose that an enemy decides to cut our maritime communications in some selected sector of the world, or over all the oceans. Suppose our newspapers begin a catalogue of disasters, reporting this carrier sunk in flames, that task force shattered to some stranded remnants, the liner United States cut down while at a full 40 knots, Lloyds of London closed, no American merchant ship on the high seas. Suppose that the enemy has carefully refrained from using nuclear weapons, or from threatening American territory. What he wants is a free hand abroad, in some area in which his internal lines of communications can suffice. (For he can no better send his merchant ships through our submarine blockade- provided we can mount one-than can we send ours through his.) In our chagrin, in our shame at abandoning our allies, in our fear of living in dingy poverty on what our own land can supply, would we then call for mutual suicide by attacking the enemy with nuclear weapons? Even our allies might not appreciate the gesture.

The threat under discussion is therefore not the nuclear missile submarine but rather the conventional attack submarine used in its classic roles-to destroy merchant ships and naval vessels, to hunt and fight other submarines, to mine and scout in enemy waters. And it need not be driven by the nuclear reactor-steam turbine plants which are currently the most economical means of propulsion for large submarines.

The newest attack submarines of the United States and the U.S.S.R. are indeed large-the size of light cruisers. However, the spectacular underwater feats of World Wars I and II were invariably accomplished by submarines displacing less than 2,000 tons. These could operate not only on the high seas, but also in waters too confined or shallow to be comfortable for today's giants. A hard core of submariners continue to believe that, in this respect, not much has changed, and that the most useful attack submarines are closer to the dimensions of the past than the present. Submarine design, which underwent an earthquake in the mid-fifties with the introduction of nuclear power, is again in a period of change. As submarines become smaller, the number of feasible propulsion systems becomes larger. They begin to include fuel cells or turbines fed by liquid hydrogen and oxygen, primary batteries, and other systems of quite enough endurance to give anti-submarine forces a severe case of the staggers.

It is now all too easy to envision a situation in which a naval war would remain tightly limited, essentially to an all-submarine war. If bulk cargo crossed contested oceans, it would do so in cargo submarines. If planes were flown over these waters, they would take off from bases with local fuel supplies.

II

The main purpose of this article is to describe the technical evolution which has produced this situation rather than to detail its economic or political consequences. Mention of a few gross manifestations may be in order, however, to put the technical issues in perspective. For countries like Japan and England, which must import major portions of their food and raw material, the new equilibrium point between submarine and surface power is merely aggravating an old and well-known weakness. Although the United States is not as dependent on imports as these extreme cases, our dependence on foreign oil, on foreign iron ore and other raw materials is growing ominously, year by year. In food, however, we are as yet basically self-sufficient.

Although Japan and England, which are dependent for their daily bread on ocean shipping, can build submarines as well as anyone, to use them offensively opens their countries to a form of retaliation almost as serious as nuclear bombardment. The economy of the United States would be crippled, but probably not destroyed, by a successful blockade. Such an outcome is less certain for the U.S.S.R. and Red China, which as yet still maintain some rough balance between their people's expectations and the productive capabilities of their own territories.

Whether the United States gains or loses from the new equilibrium, it must recognize the situation and choose a course of action, however discordant with past programs and traditions, that will capitalize on the continuing developments in underwater and associated technologies, in which it is a leader.

Overall anti-submarine capability is losing ground to submarine capability because, on balance, the latter is benefiting to a greater degree from a variety of expanding technologies. Among these, specifically, are navigation, long-range communications, satellite and undersea surveillance techniques, underwater propulsion systems, life-support systems and homing weapons. Perhaps the cruelest blow to more traditional forms of naval power is the consistent ability of the submarine to benefit on balance from sensor developments, even when these are ostensibly anti-submarine in motivation. Any sensor which can detect a submarine can more easily detect a surface ship.

As the anti-submarine forces survey the performance of the modern submarine, and review the weapons that might be used to counter it, they are forced by lack of alternatives to place more emphasis on active sonar. The concept of blunting the power of the submarine with active sonar arose well before World War II. Vice Admiral Sir Arthur Hezlet describes how:

In the decade that followed the [Washington Conference of 1921-2] the British, having failed to secure the abolition of the submarine, pushed forward experiments with countermeasures. . . . By far the most important experimental work of the period was . . . Asdic (active sonar). . . . In 1935 Hitler repudiated the Treaty of Versailles and the Anglo-German Naval Agreement was concluded. . . . In signing this agreement [which permitted Germany to build up to 45 percent of British tonnage in submarines, and up to 100 percent at a future date] the British were influenced [by their belief] that Asdic was the "answer" to the submarine. . . . The concession allowing Germany to build submarines was, therefore, not thought to be a very great risk. . . .[i]

Without question, the active sonars of this period are far more powerful and numerous than a quarter-century ago (and even more so the passive sonars of the submarine). Lavish use of active sonar energy, however, has demonstrated many embarrassing side-effects. Because of the far greater intricacy of sound propagation in the sea than of radar waves in the atmosphere, it is less likely that active sonar will eliminate submarines than that radar will eliminate planes.

If the submarine remains restricted, as in the past, to the use of passive sonar, it can now apply to these passive data a variety of digital computer techniques, and a vast store of oceanographic information. It can hear the active emissions of surface ship sonar scores, even hundreds, of miles away, and can frequently determine from them a good deal about the surface ship's position. In World War II, with its capability to run submerged on battery for only a few hours, the submarine was happy if such information helped it slip away undetected. There was little it would or could have done offensively with such information. Today, no longer restricted to a short-range torpedo as a weapon, it has a substantial number of options.

Surface ships were always in contact with the atmosphere. Essentially, they have no more use for life-support systems today than they had in Magellan's day. At the end of World War II, a submarine could stay submerged only about 18 hours, perhaps 24 as a maximum. Today, submarines can cross the Arctic under the winter ice without ever coming within hundreds of feet of the surface. After two months of continuous submerged patrol, the atmosphere in an American nuclear submarine is purer than the air in most large American cities.

Surface ships can use either nuclear propulsion or conventional fossil fuel propulsion, sometimes with only marginal effects on their efficiency. The advantages of one method of propulsion over the other are sufficiently immersed in the issues of long-term logistics that analysts can frequently make cases for both systems, and for the same ship.

About nuclear propulsion for the submarine there is no debate. It has improved underwater performance by orders of magnitude. Indeed, it can be argued that, for certain tasks and regions, the submarine does not need the indefinite endurance of the nuclear reactor, and can sufficiently thwart the surface ship with a variety of other propulsion schemes that are greatly in advance of the diesel-electric engine rooms of World War II. The ability of a submerged nuclear submarine to outrun a destroyer has now lost some of its ability to shock. Suppose some upstart submarine does the same without a shred of nuclear technology.

Fifty years ago it was said that the invention of the gyrocompass (in 1911) had made the submarine a practical device. A submerged submarine could not navigate accurately until the gyrocompass gave it a good indication of true North. Surface ships could always navigate by a variety of techniques-by the magnetic compass, by the stars (when visible), and later by Loran, Omega, Transit, and the other radio navigation-satellite techniques available to anyone who can stick an antenna into the atmosphere. To a surface ship, precise inertial navigation-of the kind the Polaris and space programs have created-is icing on the cake. To the submarine, every increase in navigation accuracy enhances its ability to execute new missions submerged.

The submarine did not operate submerged in World War II. Half the torpedoes fired in that war were fired with the submarine on the surface. Probably no torpedo has ever been fired in anger with the submarine at more than about 100 feet in keel depth. The periscope and the snorkel, instruments which forced the submarine to operate at 10 knots or less, permitted most of the submarines to submerge to a depth of about 60 feet or so, with a tell-tale pipe still extending to the surface. The world does not yet grasp what a truly submerged submarine can do under wartime conditions.

A number of ocean surveillance and communication systems-some of planetary scope-now exist. They are not all of United States manufacture. The Russian reconnaissance satellite Cosmos 318 was launched January 9, 1970. By a variety of techniques, such systems can or soon will reveal the position of surface task forces, merchant convoys and even single ships. The days are probably gone when, as in World War II, nearly half the German U-boat patrols failed to find targets and when most Allied convoys were never attacked at all. Chief among the new surveillance systems are satellites armed with a variety of sensors; a growing number of bottom-mounted sonar arrays which have great difficulty in tracking quiet submarines (but which give clear tracks on noisy surface ships); and planes of considerably greater endurance and scan rate (against surface ships) than those which flew in World War II.

Military communication networks are also evolving on a planetary scale. The new sensors, whether they be on an ocean bottom miles below the surface or in orbit several hundred miles above the earth, are now generally coupled to ground stations that examine and compare data from enormous regions. Once a target is located on this planet's surface its coördinates, coded perhaps into a single digital word, can be sent quickly to planes and surface ships. Getting such information to a submerged submarine is more difficult-but still much easier than it was in the past. In terms of the engineer's measure of communication capacity-bits per second-recent technology has added far more to the capacity of surface ship communications than to that of submerged submarines. But, for the submarine, capability has gone from near zero to a significant amount, and tactically it has been the gainer in this competition. The bulk of this technology is open to the world.

Undoubtedly a naval war of any magnitude would also involve a war of sensors, with each side attempting to destroy or neutralize the instruments which are causing it most inconvenience. The likelihood is that this would blunt but not avert the effects of these new methods of surveillance.

The most threatening of submarine-launched weapons, at least to surface ships, is the long-range homing missile. The non-homing torpedo was (and remains) highly effective against slow and unalerted ships. Torpedoes mounting homing heads may be able to attack a wider variety of targets (and may also be quite vulnerable to decoys). Neither form of torpedo is much faster or of markedly greater endurance today than those of the past. Torpedoes remain relatively ineffective against targets at long range and against craft of shallow draft, such as hydrofoils and air-supported vehicles.

Not so the air-flight missile, whose range can match or exceed that of any sensor on the submarine, and which has a vast indifference to the below- water draft or defenses of the target. There is no intention here to imply that the submarine-launched homing missile represents a weapon without a defense. A world which is attempting to blast intercontinental ballistic missiles with super-powered laser beams will not shrink from grappling with a low-flying, barely sonic air-flight missile. Whether feasible or not, however, the equipment to guard against submarine-launched missiles will become one more expensive layer of defense around ships already overburdened by a multitude of enemies. One covert factor in the demise of the battleship was the fact that, by the beginning of World War II, about one-third of its displacement was in armor plate and in passive defense measures against torpedoes.

The destruction of the Israeli destroyer Elath by Russian-built Styx missiles and the immediate Israeli acceptance of reality by shifting their own meagre naval building program to missile-armed patrol craft are actions which have caused quite different responses in this country. The actual sinking has stimulated the United States Navy into intensive investigations of defensive systems. The manner in which the Israelis extracted their five missile-carrying patrol boats from a French shipyard has been much admired, but the significance of the decision that led to their construction has gone largely unnoticed. The Israelis have obviously been impressed with the effectiveness of the missile as a naval weapon.

The larger meaning of the Elath incident, which is the Israeli policy decision regarding the use of missiles in their new construction, brings to mind an ominous parallel. In 1921, after years of the most urgent pleading, Colonel William Mitchell was permitted by the Congress to test his theory that planes could sink capital ships, and succeeded in sinking a cruiser and a battleship captured from Germany with aircraft-dropped bombs.

The implications of this test were not generally accepted. It is true enough that no single demonstration can show beyond dispute the balance between complex weapons systems, particularly when the training, motivation and actions of the men on both sides remain basic to the outcome. To place more weight on the lessons of the past than on the preaching of contemporary prophets is more often right than wrong. Dozens of naval building programs based on peacetime logic have ended in wartime fiascoes. Even when the future is read correctly, and the conclusion accepted, enough time and resources to carry it out may be lacking. Such was the case with the German Navy just prior to World War II when, in war games carried out in the Baltic, it became clear that 300 U-boats would be required to defeat the convoy system in a war with Great Britain. Immediately after Munich, plans were laid to achieve this number by 1945. But history did not wait.

Billy Mitchell died unhonored and unvindicated. Perhaps his ghost jogged Congressional memories and made Admiral Rickover's path much easier than it might have been. But Mitchell's immediate effect on our building programs for capital ships and planes was meagre.

In 1941 the United States still owned an armada of battleships for the Japanese to sink at Pearl Harbor; and the British, Japanese and Germans, each in their fashion, experienced the repeated destruction of the key symbols of their naval strength.

III

If it is true that the submarine, with its new armament and technology, now holds the upper hand, what action is indicated? What the Israelis have done will not necessarily serve the United States. The means of the Israelis are small, they are unhindered by a large investment in conventional equipment, and they have a limited geography to deal with.

The naval commitments of this country center about the protection of our ocean commerce on a global scale. If the surface navy sinks under the burden of its several defenses against different weapons, for what purpose do we shift our building programs to produce more attack submarines? We must still move goods between continents.

Cargo airplanes face some sharp limitations, particularly if the transport of jet fuels by surface tankers is interfered with. If submarine tankers replace the surface tankers, the potential for the aircraft is to a degree restored, but it will take considerable analysis to determine to what degree.

A few years ago, the cargo plane accounted for approximately one-half of one percent of all transoceanic cargo movements. Cargo planes are growing rapidly in size, with gross weights of over 700,000 pounds already realized, and with gross weights of 900,000 pounds under serious study. A 450-ton ship was of quite respectable size to a Salem merchant in the Federalist period. But oil tankers today can carry 250,000 tons.

We can probably build enough cargo planes to handle a small percentage of our transoceanic freight shipments, that is, as long as unlimited supplies of carefully refined jet fuel are available at all air terminals. If the reality of an effective submarine blockade is granted, and the area we wish to succor is suffering from a savage fuel shortage, the concept of the cargo plane as the savior of ocean commerce fails without need for a cost analysis.

Hydrofoils and air-cushion machines will probably become much larger and faster platforms than they are. Like the plane, however, they consume expensive fuels prodigiously. And although they may be more or less invulnerable to conventional torpedoes, submarines (not our own) now carry weapons capable of dealing with them.

The only viable substitute for the merchant ship is the nuclear-propelled cargo submarine. In the case of the petroleum products and other fluids which make up more than 60 percent of all ocean-borne cargo, and of the granulated products like food grains and ores which make up perhaps another 10 to 20 percent, submarine transport will cost more than surface transport, but not significantly more by the standards of blockade economics. If gasoline refined from crude delivered by tanker costs, say, two cents more per gallon than if delivered by surface ship, or if bread made from submarine-carried wheat costs a penny more per loaf, the increase is little more than that of a year's normal inflation. The submarine has at least a chance of getting through, not at a steady 25 knots along an optimum great circle course, but by dodging and hiding and slinking along at whatever speed leaves it undetected.

Dry cargo presents, of course, some special difficulties, for which many ingenious and small-scale solutions should be developed, à la airplane cargo techniques. At first glance the problems of loading and unloading submarines with packages of various shapes and sizes call for a degree of back-breaking physical labor that the docks have not seen for generations. Submarine transport costs for dry cargo, with its low average density, will be higher, relative to surface ships, than for the bulk cargoes mentioned earlier. How high depends on many factors as yet unknown, such as the packaging techniques that are used and the degree to which unloading terminals must be protected from air strikes. The first cargo submarine on record, the Deutschland, handled only dry cargo, and was a great economic success.

Possession of a fleet of cargo submarines does not eliminate the need for a fleet of attack submarines of sufficient size to deal with the enemy's submarines, to interdict his surface shipping and to cover whatever oceans the battle may spread into. In a world which shares essentially the same technology, there is no substitute for numbers. To attempt to compensate for this lack by reliance on superior performance can bring its own subtle frustrations. This Navy now builds essentially one kind of attack submarine, and in such small numbers that it attempts to crowd into each one virtually all the capability that the technology of a particular design year permits. The result is a vehicle of such gigantic proportions that its very size is interfering with its performance in missions which, particularly in limited wars, will continue to be important. During his invasion of Scapa Flow, and his subsequent sinking of the Royal Oak, Commander Prien twice grounded his U-boat, and got it off. What would he have done, in those narrow channels, with a craft having 10 times the displacement of the U-47?

Far more units than can be practically envisioned in terms of cruiser-sized submarines are needed. If designs can be considered that are uninhibited by such traditions of nuclear submarine construction as have arisen since the mid-fifties, and if missions and capabilities are matched, small attack submarines that will be useful in the closing decades of this century are distinctly feasible. "Small," however, does not mean midget. By the standards of the seventies, the submarines of World War II were small.

Such suggestions are specifics. The generality is that the large surface vessel-the mainstay of conventional naval and merchant power-has become vulnerable beyond salvage to a variety of weapons of which the submarine, armed with air-flight missiles, is king. To the several nations which, in the remainder of this century, can achieve the twin goals of (1) a significant nuclear capability and (2) a large submarine fleet, these conditions present an opportunity to paralyze our nuclear strength and to place large sectors of the world's populations under intolerable economic pressure.

The evils that can arise from international frictions are varied, and so must be the remedies. Few forms of naval warfare have been used more frequently than the blockade, and none, in the past quarter-century, has been as greatly favored by technical developments. The opportunity is now open to hold a good part of the world hostage by blocking its surface fleets. Someone will eventually grasp it. This country, dependent on ocean transport, must have a remedy in hand.

[i] Vice Admiral Sir Arthur Hezlet, "The Submarine and Sea Power." New York: Stein and Day, 1967, p. 111 and 118.

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