In 1939 he enlisted with the Royal Canadian Artillery, 14th (Midland) Field Battery of the 2nd Canadian Infantry Division. From there, he was moved to the 13th Field Regiment of the Canadian 3rd Infantry Division in their 22nd Field Battery. By 1940 he was a Lieutenant and was sent to train in Britain prior to Operation Overlord. He first saw combat landing in the 2nd Wave in a Recce Party at
Juno Beach on
D-Day. The 13th Field Regiment was interspersed with the Regina Rifle Regiment landing at "Nan" Sector of Juno Beach. After shooting two
snipers, Doohan led his men to higher ground through a field of
anti-tank mines, where they took defensive positions for the night. Crossing between command posts at 23:30 that night, Doohan was hit by six rounds fired from a
Bren gun by a nervous Canadian sentry:
[2] four in his leg, one in the chest, and one through his right middle finger. The bullet to his chest was stopped by a
silver cigarette case given to him by his brother.
[7] His right middle finger had to be amputated, something he would conceal on-screen during most of his career as an actor, sometimes with a flesh-colored glove with a "faux finger."
[9]