Merritt was sent to prison camp Oflag VII-B at Eichstätt in Bavaria. Together with 64 others, he escaped through a 120 ft tunnel during the night of 3–4 June 1943. All were recaptured after a massive manhunt. Merritt was sentenced to 14 days' solitary confinement before being transferred to Oflag IV-C at Colditz Castle. He remarked after being freed: "My war lasted six hours. There are plenty of Canadians who went all the way from the landings in Sicily to the very end." He was dismissive of his time as a prisoner of war with the words: "It was an enforced idleness. It cannot be translated into virtue."