After retiring as a player and coach, Mann became an advocate for baseball as an international sport, founding the U.S.A. Baseball Congress. He organized a 12-game tour of Japan in 1935, with an American amateur team taking eight games and dropping four against Japanese opponents. Mann went on to found the
International Baseball Federation (IBF) in 1938. Its inaugural tournament was held in England, billed as the
Amateur World Series. The
English team, composed mainly of Canadian college players, won 4 out of 5 games against the
American team. The IBF also organized subsequent championships in
Cuba in 1939 and Puerto Rico in 1941. Mann fought to include
baseball at the Summer Olympics. He petitioned the
US Olympic Committee to include baseball as a demonstration sport at the
1932 Los Angeles Games, but the committee chose football and lacrosse instead. Baseball's inclusion in the Olympics was opposed by powerful figures like
Avery Brundage, head of the USOC (and future president of the
International Olympic Committee), who was "a firm believer in the idea that there was no such thing as an amateur baseball player." Nevertheless, Mann's efforts to promote the sport got baseball was selected as a demonstration sport in the
1936 Summer Olympics played in Berlin. Originally, the United States team was scheduled to play a
Japanese team, but the Japanese withdrew. The American team was separated into two squads who competed against each other in a single game. The "World Champions" lineup beat the "U. S. Olympics" lineup by a score of 6–5 before a crowd of 100,000 people on August 12, 1936.
World War II brought Mann's efforts to an end. His plans for the
1940 Olympic Games in Tokyo – where baseball had already been approved as a demonstration sport – were scuttled after Japan forfeited the games. Mann also had hopes to establish Olympic baseball at the
1944 Games in London, but those too were canceled due to the outbreak of war. ==Later years==