1915

On May 7, 1915, the British ocean liner RMS Lusitania was sunk by a German U-boat off the coast of Ireland, resulting in the deaths of 1,198 passengers and crew, including 128 Americans. The sinking of the Lusitania contributed to growing anti-German sentiment in the United States and moved the country closer to involvement in World War I.

In November 1915, Albert Einstein presented his general theory of relativity, which revolutionized the understanding of gravity and the nature of space-time. This groundbreaking work had a profound impact on the field of physics and remains one of the most important scientific theories of the 20th century.