Seventy years ago tens of thousands of North Korean troops invaded South Korea. Over the next three years one of the bloodiest conflicts of the 20th Century claimed millions of lives. On a more positive note, though, the Korean War helped precipitate social change in the United States. Following President Truman’s Executive Order 9981, the Korean conflict became the first in which US armed forces were desegregated. It was not a smooth process but it did precede civil rights advances back home where segregation was still widespread, especially in the southern states. This is the story of why President Truman, who had himself expressed clear racist views earlier in his career, took the decision to issue his executive order to desegregate the armed forces.