No other submarine class has ever been built in the massive quantities of the Type VII U-Boat, with total production exceeding 700 before the German surrender. This is slightly more than half of the total number of submarines produced by the Third Reich, 1337. By numbers alone, the Type VII would rank among the most important attack submarines ever made, but it is even more important for the role that it played in the Battle of the Atlantic. During the most successful phase of that campaign, from 1940 to 1941, the Type VII dominated the emerging wolfpacks, and therefore represented one of the gravest threats faced by Great Britain in either war.
When Germany resumed the production of submarines in the 1930s, it began with designs that closely resembled the U-Boats of World War I. It is true that the Germans carried out experiments between the wars through a Dutch submarine company, but most of the technological progress that occurred was limited to internal improvements, such as engine and battery power. Indeed, much of the available technology was disregarded; the Type XXI U-Boat, which first appeared in 1944, could have been built a decade earlier if planners had been interested in a substantial departure from previous experience.
Instead, the Kriegsmarine focused on more familiar (and less ambitious) concepts, and the result was the Type IA U-Boat. This class was considered unsatisfactory, however, and only two were ever built. The sources of dissatisfaction included a slow dive rate, inadequate performance on the open sea, and difficulty in handling. This does not mean that the class was fatally flawed; both Type IA boats served with distinction during the war, and while both were lost in action, neither was lost as a result of technical difficulties. The Type IA class was closed, but it was used as the basis for the development of several future classes, including the Type VII.
Research into the Type VII proceeded immediately, with the first vessels being completed in 1936. The Type VII series was an extension of the Type IA, itself growing out of the UBIII series from the First World War. Types II through VI were parallel research directions, rather than incremental steps between I and VII, and of them, only the small coastal Type II ever went into production. Research and development continued in the Type VII series through 1942 before being superseded by the Type XXI in 1943.
The original Type VII became known retroactively as the Type VIIA when a new variant appeared in 1936. In all, ten Type VIIA boats were built. It was slightly slower than the Type IA, reaching 17 knots at the surface and eight knots submerged (in contrast to the Type IA’s rates of 18.6 and 8.3 knots, respectively), but it was substantially more stable when cruising at the surface. Comparisons with the UBIII of World War I show marginal improvements in speed and operational range, but in one important respect, the Type VIIA was vastly superior: it could dive 200 meters, in contrast to the UBIII’s dive depth of 75 meters.
The Type VIIA also resembled the UBIII in its armament, consisting of four forward torpedo tubes and one rear torpedo tube, with a single deck gun in support. In the case of the Type VIIA, the latter was an 88 mm gun, and 220 shells were normally furnished for it. Occasionally, this surface armament was supplemented by the placement of a 20 mm anti-aircraft gun behind the conning tower. As for torpedoes, the Type VIIA carried eleven. It was soon discovered that it had been a mistake to place the rear torpedo tube at the surface, rather than below the surface, because the water inside the torpedo could freeze during the winter. Future variants would draw the rear tube fully inside the vessel.
Other challenges included the small size of the submarine. It was just under 212 feet in length, but it never exceeded twenty feet in width. Within those boundaries, 46 men lived and worked. Thus, while the Type VIIA was capable of operating on the open ocean, it was too small to travel far. Indeed, the VIIA was not even equipped with a head in its original production. Two heads were subsequently retrofitted for the U-Boat, although during the first half of the voyage, one was used to store additional food. Despite these challenges, however, the crews of the Type VII were highly motivated. In part this can be attributed to the submariners’ specialist training as an elite force, but in part it is also tied to the fact that so many of them had trained in the even smaller Type II submarines.
The Type VIIB began production in 1936 and continued through 1940, with 24 submarines of this variant entering service. In contrast to the later Type VIIC, this was still a very small number, but several of the most effective boats came from the Type VIIB variant. The VIIB resolved the rear torpedo tube problem, but more importantly, it extended the operational range of the U-Boat by 2500 miles with provision for 33 extra tons of fuel. Most of the other changes were incremental, including the room to carry 14 torpedoes and a crew of 48, and a boost in speed to 17.9 knots at the surface. Maneuverability at the surface was also improved by the installation of two rudders.
By far the most numerous of all of the Type VII variants was the Type VIIC. Beginning service in 1940 and remaining in production through the remainder of the war, the Type VIIC numbered 568 from start to finish. Two significant changes were made to the VIIC, by comparison with the VIIB: the air intakes were raised to a higher position on the conning tower, reducing the likelihood of being flooded in choppy seas, and the 20 mm anti-aircraft gun was moved from its position on the deck behind the conning tower to a raised deck extending back from the conning tower. The latter change reduced the blind spot in the gun’s field of fire toward the bow of the U-Boat. The crew was also expanded to 52.
The Type VIIC was marginally slower than the VIIA and B variants while traveling submerged, making only 7.6 knots instead of 8. It could travel for 93 miles before needing to surface, however, and this became more important as the tide of battle turned in favor of the Allies. In 1941, a sub-variant of the VIIC known as the Type VIIC/41 was created to improve submerged performance. The hulls were strengthened, while flexible joints were employed internally; even the heads were upgraded to account for higher external pressure. While underwater speed and range were unaffected, the dive depth was substantially improved. The VIIC/41 could operate normally at depths of 120 meters (compared to 100 meters for earlier variants), while its crush depth was lowered by 50 meters to 250 m. This variant had a shorter production run, with 91 examples entering service. A further sub-variant, the VIIC/42, was planned, with further depth improvements allowing normal operations at 200 m and survival at depths up to 400 m, but it never entered production. Those resources were allocated instead to the Type XXI program in 1943.
Three other variants were projected, the Types VIID, VIIE and VIIF. Type VIIE did not enter production, and only ten examples of the other two variants (six Type VIID and four Type VIIF) were built. These were specialist vessels, with the VIID built to lay mines and the VIIF built to rearm attack submarines with torpedoes. In neither case were large numbers necessary. The Type VIID could release fifteen mines from tubes built into the rear deck, while as many as 39 additional mines could be carried internally. The Type VIIF had promise, in that it could deliver 39 torpedoes to other U-Boats for reloading at sea, but Allied dominance of the skies made this operation too dangerous to perform, and these transport submarines were used instead to deliver torpedoes to ports servicing U-Boats.
Type VII boats operated in the North Sea, the Mediterranean, and all across the Atlantic, including the coast of Africa and the Caribbean. Type VIIF transport submarines even traveled as far as southeast Asia. Built in huge numbers, operated by well-trained and highly-motivated crews and coordinated with good tactics, they inflicted a staggering amount of damage on the Allies, sinking capital ships and destroyers as well as large numbers of merchant vessels. They were easily the most important single class of submarines to serve during World War II. They were not the most advanced, however, and the resources allocated to the Type VII program delayed the implementation of truly groundbreaking designs, and the U-Boat fleet was never able to resume the offensive after the Battle of the Atlantic was called off in 1943.
Haskew, Michael. Weapons of WWII. Amber, 2012.
Konstam, Angus et al. 7th U-Boat Flotilla: Doenitz’s Atlantic Wolves. Ian Allen Publishing, 2002
Porter, David. World War II Data Book: The Kriegsmarine 1935-1945. Amber, 2010
Ross, David. The Essential Naval Identification Guide: Submarines 1914-Present. Amber, 2012
Showell, Jack Mallmann. The U-Boat Century: German Submarine Warfare, 1906-2006
Williamson, Gordon and Darko Pavlovic. U-Boat Crews 1914-45. Osprey, 1995.
© 2013. All rights reserved.