World War II: Allied forces launch the first of four assaults on Monte Cassino with the intention of breaking through the Winter Line and seizing Rome, an effort that would ultimately take four months and cost 105,000 Allied casualties.

The Allies, or Allied powers, formally referred to as the United Nations from 1942, were an international military coalition formed during World War II (1939–1945) to oppose the Axis powers. Its principal members were the "Big Four"—the United Kingdom, the Soviet Union, the United States, and China.