Back home in Moline, Illinois, from the army in WWI, Giles went to a meeting about the future of the local Three-I League team, and was elected president of the club. After success with Moline, he moved to front-office positions in the St. Louis Cardinals’ farm system, eventually becoming GM at Rochester, the Cardinals’ top minor league club. In 1937 he took over as GM of the Cincinnati Reds; two years later, the team won the NL pennant and in 1940 they became World Champions. Giles was elected club president in 1948.
In 1951, during the owners’ voting for a new Commissioner, Giles and Ford Frick stalemated through 17 ballots until Giles withdrew his name. The following year, he was elected president of the NL. During his 18-year tenure, the affable Giles presided over historic franchise shifts, including those of the Dodgers and Giants to the West Coast and the Boston Braves to Milwaukee and then Atlanta. New NL franchises were added with the Mets, Astros, Padres, and Expos. He was elected to the Hall of Fame in 1979. His son, Bill, became president and part owner of the Phillies.