Actions American Civil War 1864, February 17 – Confederate human-powered submarine H. L. Hunley sinks the Union sloop with spar torpedo, off Charleston. The H. L. Hunley thus became the first submarine to successfully sink an enemy vessel in combat, and was the direct progenitor of what would eventually become international submarine warfare. First Balkan War 1912, December 9 – became the first submarine to launch a self-propelled torpedo at an enemy ship, though the ship did not sink due to a weapons malfunction. World War I 1914, September 5 – HMS Pathfinder is sunk at the start of World War I by , becoming the first ship to ever be sunk by a self-propelled torpedo fired by submarine. 1914, September 22 – German submarine sinks three unescorted British armoured cruisers , and in approximately one hour. 1914, October 18 – German submarine sinks in the first ever successful attack on one submarine by another. 1914, October 20 – German submarine sinks in the first submarine sinking of a merchant ship during the world wars. 1915, May 7 – German submarine sinks killing 1,198 and leaving 761 survivors. The sinking turned public opinion in many countries against Germany, contributed to the U.S. entry into World War I. 1915, May 25/27 – In the morning of May 27 German submarine U-21 sinks the British pre-dreadnought battleship off the Gallipoli peninsula. Two days after the same U-boat sunk the pre-dreadnought HMS Triumph near Gaba Nepe. 1916, March 22 – German submarine is sunk by the Q-ship – a merchant ship carrying hidden weapons – HMS Farnborough in the first successful use of depth charges. (Farnborough sank the SM U-83 in 1917) World War II 1939, September 17 - German U-boat sinks HMS Courageous. 1939, October 14 – German U-boat sinks HMS Royal Oak in Scapa Flow base. The First Lord of Admiralty Winston Churchill officially announced the loss of Royal Oak to the House of Commons, first conceding that the raid had been "a remarkable exploit of professional skill and daring". 1940, October 17–19 – The most effective wolfpack of the world wars including Kretschmer, Prien and Schepke sinks 32 ships from Convoy SC 7 and Convoy HX 79 in two days. 1940, November 23 – sinks 7 Allied Merchant ships from Convoy SC-11 in only 3 hours. 1941, November 13 – U-81 strikes with a single torpedo. She sinks the following