If Reagan counts (as an actor who became a "PR Officer" and made pro-war movies and training films without ever leaving Hollywood) then LBJ and Nixon should definitely count.
William McKinley was a quartermaster in the 23rd Ohio Infantry. He remains the only quartermaster to become president. He particularly distinguished himself by bringing food and water into the battle to refresh his fellow soldiers during the lengthy battle of Antietam. He was later promoted to an infantry officer and left service at the rank of major.
Great quiz!