Surface commerce raiders were proving to be ineffective, and on 4 February 1915, the Kaiser assented to the declaration of a war zone in the waters around the British Isles. On 20 October 1914, SM U-17 sank the first merchant ship, the SS Glitra, off Norway. įor the first few months of the war, U-boat anticommerce actions observed the "prize rules" of the time, which governed the treatment of enemy civilian ships and their occupants. In the Gallipoli Campaign in early 1915 in the eastern Mediterranean, German U-boats, notably the U-21, prevented close support of allied troops by 18 pre-Dreadnought battleships by sinking two of them. On 22 September, U-9 under the command of Otto Weddigen sank the obsolete British warships HMS Aboukir, HMS Cressy and HMS Hogue (the " Live Bait Squadron") in a single hour. On 5 September 1914, HMS Pathfinder was sunk by SM U-21, the first ship to have been sunk by a submarine using a self-propelled torpedo. Main article: U-boat Campaign (World War I) Retired in 1919, it remains on display at the Deutsches Museum in Munich. During that war the Imperial German Navy used SM U-1 for training. At the start of World War I in 1914, Germany had 48 submarines of 13 classes in service or under construction. The U-19 class of 1912–13 saw the first diesel engine installed in a German navy boat. The 50%-larger SM U-2 (commissioned in 1908) had two torpedo tubes. It had a double hull, a Körting kerosene engine, and a single torpedo tube.
The Imperial German Navy commissioned it on 14 December 1906. The SM U-1 was a completely redesigned Karp-class submarine and only one was built. 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. There followed in 1890 the boats Nordenfelt I and Nordenfelt II, built to a Nordenfelt design. Dredging operations in 1887 rediscovered Brandtaucher it was later raised and put on historical display in Germany. The inventor and engineer Wilhelm Bauer had designed this vessel in 1850, and Schweffel & Howaldt constructed it in Kiel. 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.
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. U-boats were naval submarines operated by Germany, particularly in the First and Second World Wars. U-995, a typical VIIC/41 U-boat on display at the Laboe Naval Memorial