RMS Lusitania was a British ocean liner and the world's biggest ship. In 1915 she was torpedoed and sunk by a German U-boat, causing the deaths of 1,198 passengers and crew.
When she left New York for Liverpool on what turned out to be her final voyage on 1 May 1915, Germany had declared the seas around the United Kingdom to be a war-zone, and the German embassy in the United States had placed a newspaper advertisement warning people not to sail on Lusitania. On the afternoon of 7 May, Lusitania was torpedoed by a German U-Boat, 11mi (18km) off the southern coast of Ireland. She sank in 18 minutes.
The sinking caused a storm of protest in the United States, as 128 Americans were among the dead. It affected the decision by the US to declare war in 1917.