Tonton Streaming Combat! (1962) S1E12 - The Prisoner

Braddock, while on duty as Lt. Hanley's runner, is "appropriated" by a tough-talking, overbearing colonel as his jeep driver. Unfortunately the colonel decides to drive the jeep himself and his reckless driving results in an accident in which both men are knocked unconscious. When Braddock awakens he is captured by a German patrol, but since he happens to be wearing the colonel's coat--which he put on to keep warm while the colonel was zooming around the countryside--the Germans think that he actually IS a colonel, and nothing Braddock can say or do will convince them otherwise.