Truman and macarthur help please?

MacArthur was a popular general, but regardless of the cirstances in the military there is a chain of command starting with the president who is the Commander-in-Chief (a civilian). When one is given an order, one must obey it or he is insubordinate, and can be charged with a crime - insubordination. MacArthur was given the opportunity to resign - which he did. End of story.