Later, after hearing Winston Churchill's "We shall fight on the beaches" speech on the radio, MacLean and the other bush pilots enlist in the Royal Canadian Air Force, only to discover that they are considered too old for combat. They reluctantly agree to train as flight instructors for the British Commonwealth Air Training Plan. Their commanding officer is none other than Dutton. MacLean, with his brash and fiercely independent nature, clashes with the military way of doing things, and he is court-martialed and dismissed from the service for flying too low, resulting in a cadet being severely injured. For revenge, he and "Tiny" buzz the airfield when renowned Canadian First World War ace Air Marshal William "Billy" Bishop (playing himself) is speaking during the group's graduation ceremony. "Tiny" blacks out while pulling out of a dive, and his plane plummets into the ground, killing him. MacLean loses his pilot's license as a result.