Rottenführer Gunther was a brutish SS soldier who was assigned by Standartenführer Jannings to keep an eye on Hauptmann Friedrich von Hecht because of his anti-Nazi tendencies. He was an expert in radios and von Hecht, despite disliking him, often asked his advice about electronic apparatus.
He was apparently the one who tortured a captured partisan into giving up the location of a meeting place between Scarpi's resistance movement and the American paratroopers, which led to von Hecht's forces ambushing them and wiping them all out except for partisan leader Scarpi and American officer Turner, who was rescued by a group of children from the massacred village of Reanoto. Gunther didn't participate in the battle, but stood on the sidelines with von Hecht, guarding the prisoner - until Scarpi shot him from across the battlefield for betraying the resistance.
When Turner and Aldo broke into the Germans' headquarters later on to use the radio and recover the demo gear of Turner's slain men from von Hecht's office, Gunther overheard them and entered the room with his Walther P38 drawn. Turner took him by surprise and knocked the P38 from his hand. The two men fought. Turner eventually gained the upper hand and killed Gunther by breaking his neck.