In 1921, Cannell became Dartmouth's head football coach, replacing Clarence Spears. In his first season, Dartmouth posted a 6–2–1 record. After the season, Cannell's players petitioned for his return as head coach after they learned alumni were agitating to have him replaced by former Dartmouth star and Colgate coach Lawrence Bankart. The administration vehemently denied that Bankart was to replace Cannell, and The New York Times wrote the "Bankart rumor springs up every year, but usually with little or no foundation." Bankart had previously declined the position vacated by Spears, and had recommended Cannell for the job.