In response to the spread of communism during the Cold War, American containment, and Japanese occupation of Korea during World War II, a war began between China and Soviet-backed North Korea against South Korea, who was supported by the United Nations. North Korea sought to conquer South Korea and unify their countries under a communist regime. The war was characterized by continuous advancing and retreating up and down the Korean peninsula, with Seoul being captured and recaptured repeatedly.

The war ended with a truce marked by the signing of the Korean Armistice Agreement, which created the Korean Demilitarized Zone to separate the North and the South and allowed the return of prisoners. By the war's conclusion, 170,927 people were killed, 32,595 went missing, and 566,434 were wounded.