Type VII-class Submarine
Contributor: Alan Chanter
This article refers to the entire Type VII-class; it is not about an individual vessel.
ww2dbaseFollowing the near defeat of Great Britain by starvation during World War I the Germans were prohibited under the terms of the Peace Treaty from building submarines (U-boats).
ww2dbaseIn order to keep their design teams together the German Navy, between the wars, adopted a number of devious ways to circumvent the restrictions. These included the setting-up of design bureaus abroad to undertake design tasks for friendly "client" states. Thus, what might be termed the "father" of the later U-Boat, as used in Adolf Hitler's war, was the so-called Project CV707 - a single-hulled design, with saddle tanks for the Finnish submarine Vetehinen. This design, began before the expiry of the Versailles Treaty, was later "stretched" to become the basic Type VII (note that Type IV to VI were abandoned as designs) which would ultimately become the workhorse of Karl D√∂nitz's submarine fleet, with over 650 being completed before construction ceased in 1944. During the 1914-18 war German submarines had used a double hull design - the single hull with saddle tanks, as incorporated in Second World War U-boats accelerated and simplified construction but conversely made the boats more vulnerable to depth charge attacks.
ww2dbaseThe first ten units, U-27 through U-36 (designated Type VIIA) of the class were completed in 1936-37. Just 64.5 metres in length, they displaced 745 tons submerged, and carried 11 torpedoes. With a surface range was 4,300 nautical miles at 12 knots these boats were really only capable of conducting patrols in the eastern Atlantic. These first submarines were quickly developed further; through the VIIB, built between 1936 and 1940, which was slightly faster than the VIIA, and had two rudders for greater agility, to the VIIC which differed only in the addition of an active sonar and a few minor mechanical improvements, making it 2 feet longer and 8 tons heavier. Speed and range of all were essentially the same. These later boats which now carried fourteen torpedoes (some externally) had a good percentage of reserve buoyancy which when matched to the effective layout of their air-tanks allowed the boat to become submerged in less than 30 seconds. In 1944, many of the surviving boats were retrospectively fitted with a snorkel device in 1944 which allowed the use of their diesel engines whilst submerged.
ww2dbaseIn 1939 Admiral D√∂nitz, Hitler's flag officer of U-boats, had only 26 submarines capable of operating in the North Atlantic, of which just one-third could normally be kept on station at the same time. The remainder were either on passage out (or home) or refitting in Germany. Just eighteen boats were of the Type VII design, ten of them the slightly larger VIIB, but neither Hitler nor D√∂nitz had any intention of abiding by a convention that Germany had signed in 1936 which said that submarine captains should ensure, before a merchant ship was sunk, that the safety of its crew must be safeguarded. Within hours of the declaration of war the Donaldson liner Athenia was attacked by U-30, 200 miles west of the Hebrides, and sunk with the loss of 112 lives, 28 of them American citizens. Whilst it is fair to say that the Captain of U-30 exceeded his instructions in sinking this ship, it was by no means an isolated incident. During September 1939 German submarines sank 26 British merchant ships without bothering overmuch, or at all, to ensure the safety of their crews.
ww2dbaseThe British response was to set up two "Hunting Groups" each consisting of an aircraft-carrier and four destroyers, but on 14 September the carrier HMS Ark Royal only narrowly avoided being torpedoed by U-39 (which the escorting destroyers counterattacked, sank, and captured her crew). It had been a close shave. Three days later the Second Hunting Group was less lucky. The aircraft-carrier Courageous was sighted by U-29, which torpedoed and sank her with the loss of 519 lives, and successfully escaped. The Royal Navy now decided that aircraft-carriers were too valuable an asset to risk on anti-submarine patrols and Ark Royal was quickly withdrawn to take her proper place again with the Home Fleet. In October Lieutenant-Commander G√ľnther Prien took U-47 into the supposedly safe waters of Scapa Flow and there sank the Royal Navy battleship Royal Oak. Despite these setbacks, however, by the end of 1939 the loss figures were fairly encouraging. U-boats had sunk 114 ships with a tonnage of 421,156 but at the price of no less than nine U-boats lost. Considering the weak state of British escort forces at the time these figures were thought satisfactory although the Admiralty were well aware that the Germans had embarked on a very substantial programme of submarine construction.
ww2dbaseThe "First Happy Time" for the U-boats occurred from late 1940 to May 1941, Germany had declared, on 15 February 1940, that all British merchant ships would be treated as warships and over the following months the U-boats wreaked havoc on the weakly protected Atlantic convoys and their under equipped and inexperienced escorts. But by the summer of 1941 the increasing strength of the escorts, coupled with a wider spread of air cover, began forcing the U-boat "Wolf-Packs" to probe further afield in order to find less well protected targets.
ww2dbaseIn September 1941 a German submarine attacked the American destroyer Greer, south of Iceland. In October, while assisting a British convoy, USS Kearny dropped depth charges on attacking German submarines; returning fire, U-568 struck Kearny with a torpedo, killing 11 men, who would become the US Navy's first casualties in the Atlantic War. Angrily, for America was not yet at war, President Franklin Roosevelt authorised the US Navy to counter-attack. The entry of the United States into the war provided a tempting new source of virtually unprotected victims, and during a "Second Happy Time" for the U-boats they again sank thousands of tons of Allied shipping with near impunity. But the American entry into the war also meant that the convoy system would eventually be extended right across the Atlantic, and by May 1942 a combination of new warships and long range patrol aircraft drove the U-boats away from America's east coast, back once more, into mid-Atlantic where suitable targets would be less well defended.
ww2dbaseThe climax of the battle had come. D√∂nitz desperately needed to break the new, tight convoy system in order to force the British into surrender before Allied air cover could be completely extended across the entire ocean. From July 1942 to May 1943 the battle was fought out. It ended in decisive defeat for the U-boats, whose offensive equipment had failed to keep pace with new effective escort defensive capabilities such as Centimetric Radar and improved depth charge weapons.
ww2dbaseSeveral sub-variants should also be mentioned: The lightweight Type VIIC/41 (91 built) had a strengthened hull permitting a deeper depth to be reached, and the proposed stronger-hulled VIIC/42. It was fortunate for the Allies that the VIIC/42 never entered production; for its bunker capacity was increased by nearly 60 per cent and with the likelihood that it would have been able to descend to a depth of 300 metres, would have made it nearly impossible for ASDIC to detect. In addition six type VII U-boats were built as minelayers (VIID) and four as resupply vessels (VIIF). Only one of each type survived the war.
Battle of the Atlantic (Purnell's History of the World Wars Special, Phoebus Publishing, 1975)
Mark Arnold Forster, The World at War (Fontana / Collins, 1973/76)
Jane's Warships of World War II (Harper Collins, 1996)
Jane's Fighting ships of World War II (Studia Publishing, 2001)
Last Major Revision: Jul 2013
Type VII-class Submarine Interactive Map
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Winston Churchill, 1935