Gen. Douglass MacArthur had multiple reasons for being fired. In the beginning if the war he called for an unrestricted advance which would later be stopped by an overwhelming Chinese force and result in a stalemate. He repeated multiple flawed formulas which detracted from the war effort. Then during the stalemate he called for something around 10 atomic bombs to be dropped on the Korean Peninsula and the Chinese mainland which would almost surely cause a third world war. At this point President Truman had virtually no choice to replace the general at the behest of the public. This is explained very well along with the rest if the war in a series of documentaries titled The Korean War: Fire and Ice.