[1] Representing the Central YMCA, Duffy came in second in the 1911 Ward Marathon, a 20-mile (32 km) event in Toronto.
In May 1912, he ran the Spectator Marathon in Hamilton, Ontario, which served that year as the Canadian Olympic trial.
The race developed into a thriller, with fellow Canadian runner Édouard Fabre matching Duffy's pace throughout.
Only in the final mile did Duffy gain a small lead, winning the race by fifteen seconds.
Duffy's first request after his victory was for a cigarette, and after his post-race medical examination, he asked for a bottle of beer.