Adolf Hitler was a German politician and the chancellor of the Nazi Party. He appears as a in-game character in Valiant Hearts: The Great War in chapter 1.Adolf Hitler appears in the trenches calling for a dog that is similar to Walt.
He wears the same uniform that the Germans are wearing, black hair, and a square moustache.
Hitler might be calling his dog Blondi who is similar to Walt. He is a fake character and an Easter egg and one of the few soldiers, without their helmet.
Hitler was a message runner for the German Empire during World War One although his in-game representation does not portray him as a front-line soldier.