The Korean War, fought from June 25, 1950, to July 27, 1953, stemmed from the division of Korea into North and South following World War II, with escalating tensions leading to North Korea's invasion of the South. The United Nations, led by the United States, intervened to aid South Korea, resulting in a protracted conflict characterized by significant territorial changes, including the capture of Seoul and Pyongyang. Ultimately, the war concluded with an armistice, leaving the peninsula devastated and continuing Cold War tensions, with heavy casualties on both sides.