|Enlisted In||Wehrmacht, Army|
|Appearances||Full List of Appearances|
Captain Mueller is a Captain in the German Army who is the passenger in a truck that is driving down a road with a two motorcycles escort at the beginning of the episode. The truck is going through an Allied air raid when it stops on the road. Captain Mueller then exits the vehicle, goes to the back of the truck and asks his Sergeant for a map so that he could determine where they should go, since they could no longer go on to Berlin because of the heavy bombing. As he looks at the map, reading it under a lighted match, Captain Mueller quickly rejects the Sergeant's suggestion of staying where they are because of the important cargo inside the truck: If it gets destroyed, they would all be sent to the Russian Front, just in time for the Russian Winter. As he continues reading the map, he decides to have the convoy go to a nearby POW camp, doubting that the allies would bomb it. The camp in question is Stalag 13.
Captain Mueller next appears as he walks through the door into Colonel Klink's office, following Sergeant Schultz, who informs both Klink and Colonel Hogan that Mueller's group has been caught in the terrible air raid, contradicting what Klink has just told Hogan about the raid being an Allied failure. After Klink tells Schultz to shut up on the air raid, Mueller informs Klink that he needs to talk with him. When Hogan asks what it is, Schultz starts to tell Hogan when Mueller tells him to stop. Hogan and Schultz then leaves. After the two are gone, and after Mueller has made sure that they are gone, he tells Klink that he needs to stay in the prison camp with his cargo until the bombing is over. He then whispers what it is to Klink, although he doesn't tell him the complete story, claiming that it is a barrel of water.
Mueller next appears in the story, standing next to the now parked truck, looking for the truck's guard, which is Schultz. He soon finds Colonel Klink and Schultz both coming out of the back of the truck. He asks Klink what he is doing in there, and Klink replies that he is checking on the valuable cargo. He then hears Klink dismiss Schultz, who leaves, before he hears him claim that he knows what the truck's cargo actually is. Surprised by Klink's statement, he asks him how he knew. He is then surprised by Klink's answer: Klink claims that he has learned it from Hogan, who says that he has learned it from LeBeau, claiming that the water has come from a spa in Norway which has been visited by King Louis XVI and Marie Antoinette. The Captain, angered by the false information that Klink is relating back to him, snaps at Klink, before telling him that someone is making a fool out of him. He then whispers to Klink that the water inside the barrel is actually heavy water and that it is going to be used in atomic research. A surprised Klink, thinking that he might has been poisoned, asks if anything would happen to him because he drank some of the water. Mueller replies only if Berlin finds out what has happened.
Mueller's last appearance in the episode is when he shows up after Klink has just jumped out of his office because of a false fire that has been set by the prisoners as a diversion so that they could replace the barrel of heavy water with one filled with ordinary water, to help Hogan pull Klink off of the ground. He then tells Klink that the truck is safe, thanks to Colonel Hogan's quick thinking. He then comments that Hogan's help has probably helped shorten the war. A smiling Hogan agrees, but not for the reason that Captain Mueller is thinking.