Fortmann was the line coach for the Pittsburgh Panthers football team in 1944 and in 1945 served in the United States Navy in the Pacific Ocean theater of World War II.

He engaged in a medical practice in Southern California from 1946 to 1984 and was the team physician for the Los Angeles Rams from 1947 to 1963.

[2] Fortmann attended Pearl River High School, where he earned 12 varsity letters in sports and was the valedictorian of his class.

[3][5] Colgate football coach Andrew Kerr called Fortmann "the best player I ever handled.

He received straight A's as a pre-med student and graduated with Phi Beta Kappa honors at age 19.

[5] At age 19, Fortmann was selected by the Chicago Bears in the ninth and final round (78th overall pick) of the 1936 NFL draft.

[6] After being drafted by the Bears, Fortmann was unsure whether he should attend medical school or play professional football.

[5] Due to his medical school obligations, Fortmann missed most of the Bears' sessions in his first four years with the team.

The United Press called him "the heart and soul" of the Bears' ground attack that "rolled up a vast amount of yardage overland.

"[9] In August 1942, quarterback Bob Snyder called Fortmann "a perfect football player" and "the most important man on the Bear squad.

He continued to practice medicine at Pittsburgh's Presbyterian Hospital during the 1943 season, flying in on Saturdays to play with the Bears on Sundays.

[3] Fortmann enrolled at Rush Medical School at the University of Chicago, where he studied medicine while playing for the Bears.