Cold War – Diesel-Electric Submarines


HMAS Ovens – Royal Australian Navy

Diesel-electric submarines, which were also known as ‘conventional’ submarines, played a significant role in the Cold War from the very start. When NATO became operational in the early 1950s the Soviet surface fleet was generally considered to be of minor importance, since it had achieved little of strategic significance during the Second World War and by the late 1940s most of its ships were obsolescent, if not obsolete. The Soviets were outnumbered in every category, and had no ships at all to match the West’s aircraft carriers and amphibious shipping. There was, however, one area in which they were believed to pose a significant threat: that of attack by diesel-electric submarines on Allied sea lines of communication across the Atlantic. With the memories of the German U-boat attacks in the north Atlantic still fresh, this perceived Soviet threat became one of the driving influences in NATO fleet development and deployment throughout the Cold War.

Fortunately for the Allies, the revolutionary new German submarines, the ocean-going Type XXI and the coastal Type XXIII, were only just entering service as the war ended, but there was no doubt as to their excellence. Both were real submarines, whose natural habitat was below the surface and which surfaced only when forced to do so. Compared with its predecessors, the Type XXI had a stronger and much more streamlined hull, a larger battery and new control systems which enabled it to fight underwater, and its snorkel tube enabled it to recharge its batteries while remaining submerged. Its underwater speed of 17 knots made it faster than most contemporary ASW ships, especially when there was bad weather on the surface. The Type XXIII was a smaller, coastal equivalent; it too was fast and capable, although its value was limited by its ability to carry only two torpedoes.

At the war’s end, the victorious Allies shared forty U-boats between them, with top priority being given to the Types XXI and XXIII; they then scuttled the rest. On receipt of these prizes, only the French and the Soviets put a few Type XXIs into service, while the Americans and British, after very careful examination and trials, used the design innovations, first to adapt their existing submarines, of which both had very large numbers, and subsequently as the basis for new designs.


The US navy found itself in 1946 with a vast stock of very recently built and virtually identical Second World War submarines, and a wide variety of conversions was made to these between 1946 and the mid-1950s. Most were modified under the Greater Underwater Propulsive Power (the so-called ‘Guppy’) programme, in which they were streamlined, given much more powerful batteries, and fitted with sonars and snorkel tubes. These conversions remained in service with the US navy until the early 1970s, and many were transferred to overseas, navies, within NATO in particular, where for some (e.g. Greece and Turkey) they formed the backbone of the submarine service for the remainder of the Cold War.

Numbers of Second World War submarines were also converted for special roles. These included radar pickets, which were fitted with large radars to enable them to give mid-course guidance corrections to carrier-launched bombers and, later, to the Regulus submarine-launched cruise missile. Some were converted to troop transports to deliver covert parties to hostile shores, and others as seaplane refuellers.

One development in early US Cold War naval strategy was a plan to prevent Soviet submarines leaving their home ports in war by positioning large numbers of specially-developed ‘hunter/killer’ ASW submarines outside the ports. In 1951–2 three such submarines (Barracuda class) were commissioned. These were intended to be prototypes for a large class which would have been built during a future mobilization process, but the whole scheme was dropped in 1959. Meanwhile, a new class of attack submarines was built (Tang class), which incorporated the design lessons of the German Type XXI. Only six were built, followed by three of the more advanced Barbel class, before the US navy abandoned diesel-electric submarines altogether in favour of nuclear propulsion.


IN 1945 THE Soviet navy operated some 285 submarines, all of Soviet design and manufacture, of which 159 were ocean-going and 126 coastal types. These were, however, all of pre-war design and lacked modern refinements such as streamlined hulls and snorkel tubes, having been, like the submarines of other Allied navies, outdated at a stroke by the German Type XXI.

Soviet submarines were supplemented in 1945–6 by a number of ex-German submarines. Twenty Type XXIs were found incomplete when the Red Army captured Danzig, and it was assumed by Western intelligence that these were completed and pressed into Soviet service. With the knowledge available at the time, this was a reasonable conclusion, but it has since come to light that they were scrapped, still incomplete, in 1948–9. In addition, four serviceable Type XXIs and one Type XXIII (plus four Type VIIc and one Type IXC) were handed over to the Soviet navy in 1945–6 from the stock of captured U-boats administered by the British on behalf of the Allies, and all served in the Baltic Fleet until the mid-1950s. The Soviet navy also received two Italian submarines as part of the peace settlement with Italy.

Design of the first post-war submarines began in 1946, and these, based on earlier Soviet designs, entered service in the early 1950s, quickly building up in numbers. The early versions of the two larger classes, Whiskey and Zulu, were armed with deck guns but did not have snorkels. Contemporary Western intelligence assessed that these types were Soviet adaptions of the German Type XXI, but this was incorrect: they were developments of previous Soviet designs, but incorporating a few German ideas.

Western intelligence was convinced that the Soviet navy was intent on repeating the German U-boat war on the NATO sea lines of communication across the Atlantic, and the large-scale production programmes for the Whiskey and Zulu classes appeared to reinforce this theory. There was therefore some surprise when the production of both types ceased in 1957–8, and this was thought to be a prelude to production of the first Soviet SSNs, until it was discovered that a new conventional submarine was in production: the Foxtrot class.

The Foxtrot design was larger, and was in fact the first Soviet design properly to incorporate all the lessons of the Type XXI. Sixty-two were produced for the Soviet navy, and the type became the workhorse of the fleet, being found in every ocean of the world. A second, and very similar, class, the Romeo, was produced by another design bureau, but presumably the Foxtrot proved the better boat, as production of the Romeo finished with the twenty-first unit. The Romeo was, however, exported and the design and tooling were sold to China, where it was built in large numbers.

It was then expected in the West, once again, that the Soviet navy would follow the US lead and build only nuclear-powered submarines in future, but this too proved to be erroneous, and twenty Tango-class boats were built between 1971 and 1982. Displacing 3,900 tonnes, these were the largest diesel-electric submarines to be built during the Cold War and were intended to contribute to the ASW defences for the SSBN bastions. Significantly, although all other Soviet diesel-electric submarines were exported, no Tango-class submarine was ever passed to another navy.

Construction of diesel-electric submarines continued with at least twenty-four Granay-class (NATO = ‘Kilo’) boats built from 1979 onwards for the Soviet navy. A very similar but less sophisticated design, the Washavyanka class, was designed for the export market, particularly for Warsaw Pact navies.

The Soviet navy also experimented with unconventional, but non-nuclear, air-independent propulsion systems. Thirty Quebec-class boats were built in the 1950s which ran on a Russian-developed ‘Kreislauf’ system, using liquid oxygen, while the German Walter hydrogen-peroxide system was tested in the single Project 617 submarine. Neither type proved successful, but intelligence reports of the existence of the Walter project caused some alarm in the West.

Perhaps the greatest significance of the Soviet submarine fleet was that throughout the first twenty years of the Cold War its strength, capabilities and intentions were consistently overestimated by Western intelligence. This was partially due to the imposition of an information blackout by the Soviets themselves, which led to Western naval experts taking the worst-possible view (from the Western aspect) of Soviet capabilities and production, as was their wont. These estimates were reinforced by debriefings of repatriated German prisoners of war and scientists who were abducted to the USSR in 1945 and returned in the 1950s. These men gave reports which were frequently incorrect or exaggerated, or were based on the knowledge of just one element of a large programme. Western intelligence, alarmed by other elements of the Soviet threat, extrapolated from these and all too often came up with conclusions which were widely wrong. The Soviets, of course, did nothing to contradict the Western estimates.


In 1945 the British had the third largest submarine fleet and, as in the USA, early post-war efforts were devoted to converting Second World War boats. The hulls were streamlined, new and more powerful batteries were fitted, and new sensors were installed – all of which enabled these boats to serve until the 1960s and 1970s.

The British pursued the Walter hydrogen-peroxide design (and even used the services of Dr Walter from 1945 to 1948), mainly because they thought that the Soviets had a similar design and they required fast underwater boats with which to train their ASW forces. One ex-German Type XVIIB was trialled, and two British-designed boats were built. The Walter system proved to be very hazardous in service, however, and (to the great relief of the crews involved) further development was dropped.

Another British idea was to deliver 15 kT nuclear mines to the entrances to the main Soviet ports, such as Kronstadt, using specially built mini-subs, designated ‘X’ craft. These would have been towed to the vicinity of their target by a larger submarine, as had happened during the war in attacks such as that on the German battleship Tirpitz. Although four of these mini-subs were completed, the project was cancelled in 1956.

Despite developing nuclear-powered attack submarines, the British did not follow the US example by ceasing to construct diesel-electric submarines, since they considered the conventional boats to have continuing roles in the hunter/killer role (e.g. in the Greenland–Iceland–UK gap) and in clandestine operations. Accordingly, they built the eight-strong Porpoise class between 1956 and 1961, the twelve-strong Oberon class between 1957 and 1967, and, after a long gap, the four-strong Upholder class between 1983 and 1992.fn3


In 1946 France operated a small number of pre-Second World War submarines and received five ex-German U-boats in the Allied share-out, only one of which was a Type XXI. Study of the latter boat led to the Narval class, six of which were built between 1951 and 1960 and remained in service to the late 1980s. A class of four smaller boats was built at the same time, the Arethuse class; these were enlarged and much heavier-armed versions of the German Type XXIII, designed to prevent Soviet submarines attacking French convoys between North Africa and France in war. Two more classes, the Daphne class (eleven boats, 1958–69) and the Agosta class (four boats, 1972–8), completed the post-war rehabilitation of the French navy’s submarine arm.


Germany was banned from constructing U-boats after the Second World War, but when the Federal Republic entered NATO it was decided to create a new submarine service, whose mission would be to defend the Baltic and North seas in co-operation with other NATO navies. Whereas the German surface fleet was restarted using foreign ships, the submarine service used entirely German-designed and -built boats. To start with, three sunken Second World War U-boats were raised, repaired and returned to service: two Type XXIIIs in 1956 and a single Type XXI in 1958.

All post-war U-boats for the West German navy have been relatively small, with the largest, the Type 206, displacing only 500 tonnes. Twelve boats were originally to have been constructed of the first post-war design, the Type 201, but the hull was constructed using non-magnetic steel, which suffered from severe corrosion, and a new type of steel had to be developed, resulting in the Type 205. This was succeeded by the Type 206, eighteen of which were built between 1971 and 1974, and which then served as the navy’s main submarine for the rest of the Cold War.

The German submarine industry, however, remained extremely healthy, owing to orders for some seventy-three boats from overseas customers, both within NATO and from some twenty customers in South America and Asia. The main NATO customer was Norway, which purchased fifteen Type 207s, followed by six of a new design, the Type 210, for service in the fjords and the Norwegian Sea.


Other NATO navies started their post-war submarine arms using American Second World War boats supplied under the Mutual Defense Assistance Program. Italy, which had the world’s largest submarine fleet in September 1939, subsequently produced its own submarines in small numbers, as did Denmark. Greece and Turkey both opted for the German export submarine, the Type 209, with the former buying complete boats from Germany, while the latter bought a few boats direct and then undertook its own production at the navy yard at Gölcük. Spain and Portugal both bought French designs. The Netherlands produced their own, very sophisticated submarine designs, albeit in small numbers.

Thus, although the largest navy ceased to build diesel-electric submarines, the type remained very active in other navies. All Warsaw Pact members with navies operated them, as did all NATO navies except that of Belgium.

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