Sergeant Hartmann was a Waffen-SS guard stationed in the Schloss Adler. He was summoned to the Golden Hall by his superior, Colonel Kramer, to keep a watch on the seated Olaf Christiansen, Lee Thomas and Edward Carraciola, who Johann Schmidt claimed were imposters. But truth, Schmidt was the imposter. He was actually undercover British spy John Smith. An enraged Kramer yelled for Hartmann to attack Smith, but the Welshman acted quicker, knocking the Nazi sergeant unconscious with one punch. Afterward, the knocked out Hartmann was injected with a sleeping drug which kept him and the other Nazis in the Golden Hall sound asleep for the remainder of the Allies' mission. Hartmann's fate after this is unknown.
- Hartmann doesn't survive in the film. When Kramer yells for him to kill Smith, instead of knocking him out, Smith shoots Hartmann with a silenced Walther PPK, killing him.