The Army Chief of Staff , General of the Army Dwight D. Eisenhower , met with Groves on 30 January 1948 to evaluate his performance . Eisenhower recounted a long list of complaints about Groves pertaining to his rudeness , arrogance , insensitivity , contempt for the rules and maneuvering for promotion out of turn . Eisenhower made it clear that Groves would never become Chief of Engineers . Groves realized that in the rapidly shrinking postwar military he would not be given any assignment similar in importance to the one he had held in the Manhattan Project , as such posts would go to combat commanders returning from overseas , and he decided to leave the Army . He was promoted to lieutenant general on 24 January 1948 , just before his retirement on 29 February 1948 in recognition of his leadership of the Manhattan Project . By special Act of Congress his date of rank was backdated to 16 July 1945 , the date of the Trinity nuclear test
Trinity nuclear test
Trinity (nuclear test)
Leslie Groves