Wagner was a lieutenant in the East German Army who made it across the border with his little sister and promptly joined the US Army as a private. He went through Special Forces training, became a first lieutenant, served in Germany and Africa before going to Vietnam, where he served with honor until a Viet-Cong grenade left him paralyzed.
If you read a detailed history of Larry Thorne, such as Michael Cleverley's The Times and Life of Larry Thorne, there are a great many similarities between Thorne and Wagner.