The midget submarine threat has undeniably resurfaced and except in Sweden, harbor defenses have largely fallen into disrepair or been shamefully neglected. Most thinking has been concentrated on the large submarines far out at sea; hence, standard anti-submarine measures have not been designed to cope with what, more than a century ago, the prescient French journalist Gabriel Charmes called Ia poussiere navale — mere specks of dust, the tiny torpedo boats of his day which he declared would replace giant battleships. Charmes would view today’s situation sardonically.
The arguments for and against high-performance small submarines will doubtless continue; but meanwhile it might be worth looking closely at veritable midgets, right at the bottom of the size-scale, in light of the technology now available.
There are few people still around who have had actual seagoing experience in midgets; and some, especially those who were connected with the short-lived USS X-1 in the 1950s might well say that once tried was enough. But those who were lucky enough to drive an excellent British X-craft or a German Seehund — both types arguably way ahead of a large field of mini-submarines during World War ll and the immediate post-war years – will remember how extraordinarily powerful and effective the tiny craft could be. Even some of the so-called human torpedoes – by no means submarines proper — were devastating. The Italian Maiale (“pigs”) not only achieved significant tactical triumphs (as did similar British ‘chariots’) but they upset the strategical balance of naval power in the Mediterranean when, led by de Ia Penne on 21 December 1941, they crippled the 30,000-ton British battleships Valiant and Queen Elizabeth in Alexandria Harbor. Then, the British X-5 and X-6 –true midget submersibles- returned the compliment by putting the 42,000-ton German battleship Tirpitz out of action in September 1943. “‘The Beast”, as Churchill called her, was lying far up in a Norwegian fjord behind supposedly impregnable defenses where no other attackers could reach her. She was sheathed in 15-incb armor and bad a crew of 2,500. Yet eight men, in two tiny craft, with half-inch pressure hulls, prevented her from ever setting out to sea again. The British mini-submariners had removed at a stroke the greatest single threat to Russian convoys which bad kept two American battleships and the bulk of the British Home Fleet on guard – when those important units were desperately needed elsewhere.
These were not the only midget successes. German Seehunds sank something in the order of 100,000-tons of shipping between January and May 1945. Besides other harbor attacks, X-craft preceded the Normandy invasion fleet to mark Sword and Juno beaches.
In addition to over-engineered and suicidal human torpedoes, the Japanese devised some excellent midgets much better than those which initially attacked at Pearl Harbor. Yet, despite vast numbers of mini-subs being built, the Japanese achieved practically nothing. True, an unsophisticated BY seriously damaged the British battleship Ramillies at Diego Suarez at the end of May 1942 — a feat that deserves more recognition. But other Japanese midget operations were, on the whole, less than impressive. This raises some questions. Bearing in mind that midgets of various kinds were available in huge numbers to the Japanese Navy, why was it that they had so little impact on the war? Why, by contrast, were the Italians along with the British, so very much better at mini-submarine operations?
One should look at the answers to those questions before assessing mini-submarine underwater warfare today, because the midgets are far more relevant than they were during World Warn. There were several crucial factors which spelled the difference between success and failure — and the Russians as is their wont have almost certainly recalled them and taken to heart the wartime lessons learned. In summary:
o attacks at source, i.e. in ports and anchorages, had a strategic effect out of all proportion to the effort involved;
o suicide missions were doomed in more than the obvious way, from the start. Kamikaze tactics worked with aircraft because the pilots attacked with exhilarating speed and a fairly short flight time. But prolonged mini-sub submerged operations, requiring meticulous navigation and the ultimate precise positioning of weapons, did not succeed when the small craft was easily detected by visual or radar observation of the intruder. It was invariably necessary to expose parts of the submersible for long periods in order to hopefully estimate where it might be as it closed its target Thus, destruction before death at the target was all too likely;
o thorough, realistic training lasting months rather than weeks, was, and is, mandatory. The Japanese failed by and large to provide it. Moreover, considerable risks had to be accepted during pre-operational exercises. (That proved to be a primary reason for disbanding the British X-craft Unit in the late 1950s.);
o a single mini-sub operator, alone by himself (as in certain German midgets) tended to lose heart quickly even if he could cope with the control and attack problem – which often enough he could not. There had to be at least two in a crew and, for lengthy operations, four was about the minimum;
o covert attack units had to be allowed to develop team spirit in their own unconventional way. A very special kind of man was required. Self discipline was more important than discipline by rank. Naval orthodoxy necessarily went by the board;
o no enemy antisubmarine or anti-torpedo defenses wholly defeated an assault by determined and properly trained midget operators. They were a hindrance, and frequently they trapped a craft, but a few of the mini-attackers usually got through;
o complexity in design of the midgets was disastrous when it came to the test of war. Simplicity and ruggedness won the day.
There is a lot of meat in these seven points. The Soviets, now reckoned to have a couple of hundred midgets, have long been chewing on it. Since 1962 very small Soviet submersibles have frequently penetrated Swedish waters without being caught; and they are suspected of having been active off Brazil, in San Francisco Bay, around Japan and South Korea – and virtually going unchallenged. This suggests that the above lessons have been duly digested. With today’s greatly increased submerged endurance, and with accurate navigation during totally submerged transit, midgets can now arrive at their targets undisclosed, efficiently carry out their missions and make their getaway – all at little risk.
Whether or not a midget can attack targets in the open sea depends on its propulsion and weapon systems; and those systems together with the number of weapons carried, determine its size. Given that propulsion and endurance are adequate, the minimum weapon load to make a coastal or bluewater operation worthwhile is probably two heavyweight torpedoes (or missiles) or four lightweight ASW torpedoes for each unit in a sizeable flock of submarines. Seehund, for example, carried two external torpedoes, had a two-man crew, was only 11.9 meters long and had a displaced tonnage of 14.7 tons, but had such a limited surface and submerged endurance that it could only be used out to about 100 miles from its base, at most. This made it good only for defence against an invasion fleet or to interdict inshore traffic, but not much else. Nevertheless, a large number of modernized Seehund successors, operating from a Soviet-controlled Norwegian port in war and with their range greatly extended by present-day technology (using fuel cells, or far higher capacity batteries, or closed-cycle engines like the Stirling or Maritalia diesels) might very well swamp the ASW defenses of an incoming amphibious force. Bearing in mind that the USSR has historically considered submarines as essentially defensive, it would not be at all surprising to find that a proportion of the Soviet midgets are intended for that purpose.
Low-frequency active sonar is not likely to have much joy against very small submerged attackers. Nor are the usual ASW weapons well suited to destroying them. During World War II, Gennan midget commanders noted that depth-charge explosions actually illuminated the inside of their craft through the plexiglass dome. Yet no damage was done. The reason seems simple: most big submarines were cracked or ruptured by reason of shock waves arriving at fractionally different times along the length of the submarine. It was this differential, causing a kind of whip effect, which seems to have resulted in destruction, according to German guesses. A midget on the other hand was too small for that to happen. Clearly, a charge detonating against the hull would write it off. But if it was displaced, the shock waves, although rocking the craft severely, did no real damage. German midget submariners offered the analogy of a long plank of timber in a heavy sea where it would likely be smashed; but a matchstick tossed into the waves would simply ride with them. A similar analogy might be applied to low-frequency active sonar.
That aside, the primary and logical purpose of a true midget submarine is to intrude where its big sisters cannot or dare not trespass. Up estuaries, deep into harbors, along hazard-strewn shorelines, etc. are the mini-subs’ preserve.
Little has been openly published by intelligence sources about current intruding Soviet midgets. It seems certain though, from tracks photographed on the seabed, that they count amphibians amongst them. There is something to be said for an amphibious vehicle if heavy stores for agents have to be humped onto a shelving shore — and there is no need for the amphibious mini-sub to come right out of the water. Perhaps more significantly, an amphibian would be useful for interfering with seabed communication links. It is also reasonable to assume t~at the Soviets have a general purpose class of midgets for harbor penetration which would be armed principally with ground and limpet mines. Finally, some “Seehundskis” for anti-surface and possibly anti-submarine work could be expected. Needless to say, all intruder types are likely to be equipped with exit and re-entry chambers. Spetznaz troops, male and female, are the obvious choice for agents and combat swimmers. But the actual crews should be “special” submariners conforming to the lessons learned during a war.
Another lesson that’s been learned is that midgets can be constructed easily and cheaply, while the building process, training and the operational base can be entirely secret. Hence it is not surprising if detailed intelligence is in fact lacking on the Soviet midgets.
However, as always, it is best to look ahead. While the Soviet mini-subs briefly outlined are probably of yesteryear’s technology, there is a need to see what is possible today and tomorrow – and for that there are some good ideas from present developments which can be highlighted. A present closed-cycle, diesel-propelled midget, for example, with an estimated 200 meter diving depth, and 200-mile range at 6 knots, serves to indicate where midget submarines are headed. Inside a 29-ton displacement-envelope there is a large “moonpool” kind of chamber amidships which can be used for planting mines or as a lockout chamber for swimmers who can be deployed out through the bottom hatch after being brought to saturation pressure inside the chamber. In the case of laying ground mines, they would be lowered through the bottom hatch using block and tackle while the midget submarine hovered just above the seabed. Then, assuming that the bottom is mud or sand, an ingenious method of letting the mine dig itself deep into the bottom is offered. A diver in the moonpool using a pole with a vibrator attached to it can circle the bottomed mine with the device and vibrate the soil around the recumbent mine, making it sink under its own weight deeper into the bottom. Buried, it is much more difficult for mine-hunters to find and dispose of. As for the radiated noise of such a midget, there is no exhaust system, which reduces airborne noise considerably, while a thick internal quilting around the engine would reduce radiated noise to sea. The midget’s navigation system could be an adaptation of the wellproven Doppler equipment used for berthing large tankers. Operating at between 500 and 600 kHz it is undetectable at ranges in excess of 500 meters, even with specially tuned listening equipment. The Doppler against the seabed produces an estimated position which is true within one mile in a hundred. In conjunction with a gyro which is selfcompensating for precession and with occasional satellite fiXes, a commander will be able to readily find his way with the aid of a computerized display to his target, even in the most confined channels. This means that today’s mini-sub can remain totally submerged for a long run in to a target -almost eliminating the chances of being detected both getting there and getting away.
Two major roles are envisaged for such midget submarines. As an intruder, the craft can carry mines for seeding in critical channels and in such a way that they cannot easily be swept, and they would be planted in waters of generally less that 20 meters. Alternatively, the midget can be equipped with two lightweight torpedoes and an electronic periscope. In the defensive role, a high·resolution scanning sonar can be fitted for controlling six miniature torpedoes for use against swimmer delivery vehicles, or for neutralizing combat swimmers. This should prove to be a more effective method for combatting this underwater threat to coastal areas of the world, than the static installations under present consideration in the West.
In accordance with the last wartime lesson mentioned earlier, simplicity and ruggedness are keynotes of the design of today’s midgets. What might seem like sophistication is actually very straightforward and uncomplicated.
Above all, midgets can strike at source before enemy ships and submarines spread out in the open ocean. As President Woodrow Wilson said in 1918, “I despair of hunting for hornets all over the sea when I know where their nest is.”
Indeed, if any enemy can be destroyed in the nest or be prevented – by mines for example ·- from leaving it, this particular application of seapower by the attacker results in command of the sea. Midget submarines, in their renewed configurations, enjoy the potential for conferring just that kind of sea power.
It might well be asked why other navies (outside the USSR and Italy) have not pursued the midget concept vigorously. This is because most navies have apparently been mesmerized by immensely powerful, and enormously expensive, underwater giants and have forgotten the menace of the midgets – a menace which an enemy could be made to face, as well as mainly ill·equipped defenders.