3, During the Korean War, Truman relieved MacArthur of command because of (a) cowardice, (b) insubordination, (c) military incompetence, (d) treason. 4. President Eisenhower failed in his effort to negotiate a nuclear test ban treaty with the Soviet Union because of (a) growing concern about the "missile gap," (b) the shooting down of the U-2, (c) tension in Vietnam, or (d) violence in the Civil Rights movement.