World War II from #AtoZChallenge – U is for U-Boat

WORLD WAR II FROM A TO Z

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U-995 Type VIIC at the Laboe Naval Memorial

U-boat is the anglicised version of the German word U-Boot, a shortening of Unterseeboot, literally “undersea boat”.   Although at times they were efficient fleet weapons against enemy naval warships, they were most effectively used in an economic warfare role (commerce raiding), enforcing a naval blockade against enemy shipping. The primary targets of the U-boat campaigns in both wars were the merchant convoys bringing supplies from Canada, the British Empire, and the United States to the islands of the United Kingdom and (during the Second World War) to the Soviet Union and the Allied territories in the Mediterranean.

A convoy and its life-giving cargo–ever vulnerable to attack

During World War II, U-boat warfare was the major component of the Battle of the Atlantic, which lasted the duration of the war. Germany had the largest submarine fleet in World War II, since the Treaty of Versailles had limited the surface navy of Germany to six battleships (of less than 10,000 tons each), six cruisers and 12 destroyers. Hmm I guess Hitler found himself a loophole by going undersea.

A German U-Boat at sea, with crewmen perched on the sub’s tower, scanning the horizon for targets.

In the early stages of the war, the U-boats were extremely effective in destroying Allied shipping, initially in the mid-Atlantic up until 1942 when the tides changed, where there was a large gap in air cover. There was an extensive trade in war supplies and food across the Atlantic, which was critical for Britain’s survival. This continuous action became known as the Battle of the Atlantic, as the British developed technical defences such as ASDIC and radar, and the German U-boats responded by hunting in what were called “wolfpacks” where multiple submarines would stay close together, making it easier for them to sink a specific target.

From packed submarine nests such as this one, U-boat wolf packs ventured forth into Allied sea lanes to terrorize merchant convoys.

Later, when the United States entered the war, the U-boats ranged from the Atlantic coast of the United States and Canada to the Gulf of Mexico, and from the Arctic to the west and southern African coasts and even as far east as Penang. The U.S. military engaged in various tactics against German incursions in the Americas; these included military surveillance of foreign nations in Latin America, particularly in the Caribbean, in order to deter any local governments from supplying German U-boats.

CG22165A Crewmen from the Spencer (WPG-36) picking up survivors from a Nazi U-boat just before it sank. Photo courtesy of NARA.

CG22164A Spencer (WPG-36) German prisoners from a sunken U-boat in the North Atlantic enjoying the food on the Spencer.Photo courtesy of NARA.

Because speed and range were severely limited underwater while running on battery power, U-boats were required to spend most of their time surfaced running on Diesel engines, diving only when attacked or for rare daytime torpedo strikes. The more ship-like hull design reflects the fact that these were primarily surface vessels which had the ability to submerge when necessary. This contrasts with the cylindrical profile of modern nuclear submarines, which are more hydrodynamic underwater (where they spend the majority of their time) but less stable on the surface. Indeed, while U-boats were faster on the surface than submerged, the opposite is generally true of modern subs. The most common U-boat attack during the early years of the war was conducted on the surface and at night. This period, before the Allied forces developed truly effective antisubmarine warfare (ASW) tactics, which included convoys, was referred to by German submariners as “die glückliche Zeit” or “the happy time.”

The U-boats’ main weapon was the torpedo, though mines and deck guns (while surfaced) were also used. By the end of the war, almost 3,000 Allied ships (175 warships; 2,825 merchant ships) were sunk by U-boat torpedoes.