German U-boats

U-boat is the anglicised version of the German word U-Boot [ˈuːboːt], a shortening of Unterseeboot, literally "undersea boat". While the German term refers to any submarine, the English one (in common with several other languages) refers specifically to military submarines operated by Germany, particularly in the First and Second World Wars. Although at times they were efficient fleet weapons against enemy naval warships, they were most effectively used in an economic warfare role (commerce raiding) and 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 United Kingdom and (during the Second World War) to the Soviet Union and the Allied territories in the Mediterranean.

Austro-Hungarian navy submarines were also known as U-boats.

The first submarine built in Germany, the three-man Brandtaucher, sank to the bottom of Kiel harbor on 1 February 1851 during a test dive. The inventor and engineer Wilhelm Bauer had designed this vessel in 1850, and Schweffel & Howaldt constructed it in Kiel. Dredging operations in 1887 rediscovered Brandtaucher; it was raised and put on display in Germany.

There followed in 1890 the boats WW1 and WW2, built to a Nordenfelt design. In 1903 the Friedrich Krupp Germaniawerft dockyard in Kiel completed the first fully functional German-built submarine, Forelle, which Krupp sold to Russia during the Russo-Japanese War in April 1904. The SM U-1 was a completely redesigned Karp-class submarine and only one was built. The Imperial German Navy commissioned it on 14 December 1906. It had a double hull, a Körting kerosene engine, and a single torpedo tube. The 50%-larger SM U-2 (commissioned in 1908) had two torpedo tubes. The U-19 class of 1912–13 saw the first diesel engine installed in a German navy boat. At the start of World War I in 1914, Germany had 48 submarines of 13 classes in service or under construction. During that war the Imperial German Navy used SM U-1 for training. Retired in 1919, it remains on display at the Deutsches Museum in Munich.

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