The sinking of the Lusitania on May 7, 1915, was significant as it heightened tensions between the United States and Germany during World War I. The British ocean liner was torpedoed by a German U-boat off the coast of Ireland, leading to the deaths of 1,198 passengers, including 128 Americans. The attack provoked widespread outrage in the United States and contributed to changing public opinion against Germany, highlighting the dangers of unrestricted submarine warfare. Although the U.S. did not enter the war immediately, the Lusitania incident played a crucial role in the eventual decision to declare war on Germany in 1917.