John Allen Mann, or "Allen" as he was known to his friends, was born on June 25, 1909, in Bradford, Ohio. He was raised on a Washington Township farm in Shelby County, Ohio. As a youth, Allen was recognized for rescuing a Piqua youth from drowning in the Miami River. Allen had learned to swim one year prior to this incident, having been thrown in the same river by some older boys.
As a teen, Allen was crippled in an attempt to "hop a train". He had jumped on a boxcar. As he pulled himself up, the couplings joining each car smashed his left foot. He was found unconscious when the train stopped in St. Louis. The accident required five toes and part of his foot to be amputated.