Truman clashed with General Douglas MacArthur over combat maneuvers during the Korean War. MacArthur’s soldiers and UN troops had pushed North Korean forces past the 38th Parallel (the dividing line between North and South Korea). However, when MacArthur pushed into North Korea, China sent thousands of troops there, forcing a retreat by the UN forces.

MacArthur urged the president to approve of military action against China. Truman, fearing the development of World War III, declined. This led to the Korean War ending in a stalemate rather than a clear victory. MacArthur publicly challenged Truman’s authority, declaring that “there is no substitute for victory.” Truman fired MacArthur for challenging his authority as commander in chief.