Markle escaped with 2 POW's from Stalag Luft I. They were recaptured the following day and were imprisoned for 3 weeks prior to being sent to Stalag Luft III.
I think he did the right thing to try to escape because by defending his country he was imprisoned. The conditions were very bad. He did not know what they would do to him. If I were in his position, I would run away too instead of being killed.