10. MacArthur demanded overall command of all forces involved in the invasion
Throughout the Pacific war, overall command of the forces in the huge theater was divided. Unlike in Europe, where supreme authority was held by Eisenhower as the commander of Supreme Headquarters Allied Expeditionary Forces in Europe (SHAEF) the Pacific had Admiral Chester Nimitz in command of the Central Pacific, General MacArthur as commander in the Southwest Pacific, and Lord Louis Mountbatten in command of the China Burma India (CBI) theater. Both MacArthur and Nimitz wanted the authority for the proposed invasion of Japan, and their chiefs in Washington were divided over which it should be, based on longstanding American inter-service rivalries.
A proposal arose, most likely from MacArthur, that a temporary rank is created for him which would make him senior in authority over all other service ranks. The idea of whether or not to appoint MacArthur as a sort of Generalissimo, which would also make him senior in theory to the Joint Chiefs of Staff, never went beyond the discussion phase, and according to Admiral Ernest King, the Naval Chief of Operations, was never under serious consideration. In the final event, Nimitz agreed to place the Navy under MacArthur’s authority only if the situation on the ground in Japan dictated such a necessity, for example, if it was necessary to withdraw the invading troops in the event of a repulse.