Kurt Steiner
...I recently read a book, or biography,(publ 1981) based on interviews with one Norwegian veteran of the Foreign Legion.
In this biography Kurt Steiner is a central figure, and was serving as "foot-soldier" of the Legion, including fighting in Vietnam in the 40s/50s. The "Eagle Story" is referred to in the book, but no mention of the film. The whole book is smack full of details and facts, and there seems to be no reason to doubt that the reference to Steiner is real. There is also one photo of Steiner in the book, taken whilst holding a post somewhere in Vietnam...
People have perhaps heard about this before...thought it was fairly interesting anyway