In 1942, Sismey was seriously wounded when the flying boat of which he was the co-pilot was attacked by fighter aircraft of the Vichy French Air Force, over the Mediterranean Sea off Algeria. He received multiple wounds in his back from shrapnel. These injuries sometimes affected Sismey long after his recovery: he had to leave a ground during at least one game, because a piece of metal had begun to work its way out of his body. During the Services XI's tour of India in 1945, Sismey withdrew from the team temporarily so that surgeons could remove shrapnel.