was unsure whether he should attend medical school or play professional football. Bears owner George Halas persuaded Fortmann that he could do both and advanced funds to Fortmann for medical school. After speaking with Halas, Fortmann signed with the Bears in May 1936. At the time, he was the youngest person ever signed by an NFL team. Due to his medical school obligations, Fortmann missed most of the Bears' sessions in his first four years with the team. In 1941, during his medical internship, he described pro football as "just the means to an end", the end being practicing medicine as a surgeon. Yet, Fortmann became fiercely loyal to Halas, saying: "Halas is the salt of the earth. There is nobody I admire and respect more than him." Fortmann remained with the Bears for his entire professional football career, lasting for eight years from 1936 to 1943. He appeared in 86 games for the Bears. By 1939, Fortmann had established himself as one of the best most valuable players in the NFL. In voting by NFL coaches for the 1939 All-Pro Team, Fortmann received 37 points, the second-highest individual vote of any player. Fortmann was team captain of the Bears starting in 1940. As team captain, he led the Bears to back-to-back NFL championships in 1940 and 1941 with records of 8–3 and 10–1. After the 1940 season, Fortmann was rated as the best lineman in the NFL. The United Press called him "the heart and soul" of the Bears' ground attack that "rolled up a vast amount of yardage overland." In the 1940 NFL Championship Game, the Bears defeated the Washington Redskins by a 73-0 score. Fortman later cited the 1940 championship game as proof of Halas' skill as a "master of psychology." The Bears had lost to the Redskins three weeks earlier, and Fortmann recalled that Halas kept reminding the Bears of that defeat every day, and when the team took the field for the championship game, "they were keyed the highest emotionally I ever saw them." In August 1942, quarterback Bob Snyder called Fortmann "a perfect football player" and "the most important man on the Bear squad." The 1942 Bears compiled a perfect 11–0 record in the regular season and won the Western Division championship, but lost to the Washington Redskins in the 1942 NFL Championship Game. Fortmann announced his retirement from the NFL in January 1943,