- World War II Ends: The German Instrument of Surrender was signed in Reims, France, marking the official end of World War II in Europe. The document was ratified in Berlin on May 8, but many consider May 27 as "Victory in Europe Day" or "V-E Day."
- V-E Day Celebrations: Celebrations erupted across the Allied nations as news of the German surrender spread. People danced, sang, and rejoiced in the streets, marking the culmination of years of conflict and sacrifice.
- Harry S. Truman Becomes President: In the United States, Harry S. Truman took the oath of office as the 33rd President of the United States following the death of Franklin D. Roosevelt on April 12.
- USS Indianapolis Sunk: The American heavy cruiser USS Indianapolis, which had just delivered components for the atomic bombs that would later be dropped on Hiroshima and Nagasaki, was torpedoed and sunk by the Japanese submarine I-58. Over 800 crew members lost their lives, while hundreds more endured several days in the water before rescue.
- German Surrender Ceremonies: German generals signed surrender documents in various locations, including in Reims and Berlin, to officially end the war. The Soviet Union held its own separate signing ceremony on May 8, leading to the divergence in commemorating V-E Day between Western Allies and the Soviet Union.
- United Nations Conference: The United Nations Conference on International Organization continued its deliberations in San Francisco, California. The conference aimed to establish a new international organization to maintain peace and security, which eventually became the United Nations.
- Postwar Planning: Leaders of the Allied nations began discussions and planning for the postwar period, including issues related to the reconstruction of Europe, the establishment of a new international order, and the denazification of Germany.