President Truman's relief of General Douglas MacArthur creation of a professional military. This made civilian control increasingly problematic when coupled with the constitutional division of powers between the President as commander-in-chief, and the Congress with its power to raise armies, maintain a navy, and wage wars. In relieving MacArthur for failing to "respect the authority of the President" by privately communicating with Congress, Truman upheld the President's role as pre-eminent. Harry S. Truman became President of the United States on the death of Franklin D. Roosevelt in 1945, and won an unexpected victory in the 1948 presidential election. He was the only president who served after 1897
President Truman's relief of General Douglas MacArthur was no requirement to do so. This began to change after the Spanish–American War, when American military forces started to be deployed overseas in the Pacific, Asia and the Caribbean for extended periods of time. The concept of the theater of war developed during World War II. At such a senior level of command, military and political issues tended to merge. As theater commander in the Southwest Pacific, MacArthur had been accountable to the Australian government as well as his own, making him, in President Roosevelt's words to him, "an ambassador as well as Supreme Commander." MacArthur's less than wholehearted