MacArthur conceived of the Korean war as a holy war; he kept talking about "unleashing Chiang Kai-shek," then holed up in his island fortress on Formosa, and launching atomic strikes, all of which made Truman, the Joint Chiefs of Staff and the other UN countries involved very nervous.
For Harry Truman and the Joint Chiefs, Korea was an exercise in containment, but that made it a very frustrating war for many Americans. It meant that in this war the United States was not aiming for total victory, but for more limited, and more ambiguous, results.
There is a tradition in American government that the military is subordinate to the civilian leaders. Generals do not make statements about policy without first clearing them with their superiors. But MacArthur, used to ruling in Japan, ignored the chain of command, and began writing letters about what the United States should do in Korea.
He sent a letter to the Veterans of Foreign Wars saying that Formosa would be a fine place to launch an aggressive campaign against China. After the Chinese entered the war -- something MacArthur had assured Truman would never happen -- MacArthur wrote to Speaker of the House Joe Martin saying the United States could only win by an all-out war, and this meant bombing the Manchurian bases. So Harry Truman fired him, and evoked a firestorm of criticism from conservatives who believed Truman to be soft on communism.
But there is no question that Truman was absolutely correct. Whether his overall policy was right or wrong, the American Constitution commits control of foreign policy to the president and not to the military.
As Truman explained, avoidance of World War III while containing aggression was a difficult line to walk, but that was the policy the United States had decided upon. No soldier, not even a five-star general, could unilaterally challenge that policy without disturbing an essential element of democratic government.
