I just learned the other day that George Marshall began planning for the postwar demobilization of the Army on April 14, 1943, before the landings on Sicily, and indeed before a single American soldier was fighting in Europe. That's confidence.
But no, George Marshall was not perfect. On July 16, 1946, the Pentagon "suspended Army enlistment of Negroes (except certain specialists) because Negro recruits enrolled at a rate of 1 to every 5 white recruits, exceeding Army's 1 to 10 ratio." I read in another book that that ratio was set at the end of the Civil War, so hard to blame on Marshall. But still.
Finally, I didn't know that an estimated 20,000 American servicemen publicly demonstrated in Manila in 1946 to be allowed to return to the United States sooner than planned.
(All three facts from the Army's official 1952 History of Personnel Demobilization in the United States Army)
Library of Congress