who invented the first submarine used in war
History of submarines The submarine became a potentially viable weapon with the development of the first practical self-propelled torpedoes. The Whitehead torpedo was the first such weapon, and was designed in 1866 by British engineer Robert Whitehead. His 'mine ship' was an 11-foot long, 14-inch diameter torpedo propelled by compressed air and carried an explosive warhead. The device had a speed of 7 knots (13 km/h) and could hit a target 700 yards (640 m) away.[27] Many naval services procured the Whitehead torpedo during the 1870s and it first proved itself in combat during the Russo-Turkish War when, on January 16, 1878, the Turkish ship Intibah was sunk by Russian torpedo boats carrying Whiteheads.
Sinking of the RMS Lusitania The sinking of the Cunard ocean liner RMS Lusitania occurred on Friday, 7 May 1915 during the First World War, as Germany waged submarine warfare against the United Kingdom which had implemented a naval blockade of Germany. The ship was identified and torpedoed by the German U-boat U-20 and sank in 18 minutes. The vessel went down 11 miles (18 km) off the Old Head of Kinsale,[1]:429 Ireland, killing 1,198 and leaving 761 survivors. The sinking turned public opinion in many countries against Germany, contributed to the American entry into World War I and became an iconic symbol in military recruiting campaigns of why the war was being fought.[1]:497–503