After college, Gardner would continue to have success at the
U.S. Amateur. Gardner won the event in 1915. The following year, he also reached the finals but lost. Gardner enlisted in the
Army in 1917 and served in
France during
World War I as a lieutenant in a field artillery unit. After the war he returned to Chicago and joined a stock brokerage firm where he spent the rest of his career. He served as president of the Chicago District Golf Association (CDGA) for many years and also served on several
United States Golf Association committees. Gardner continued to have success as an amateur golfer. In 1920 and 1921, respectively, he reached the finals of the British Amateur and U.S. Amateur. He won the CDGA Amateur Championship three times: in 1916, 1924, and 1925. Gardner also was national champion in another sport,
racquets. He and Howard Linn won the national doubles racquets championship in 1926 and 1929. ==Personal life==