Hey Mike,

PS: For some nasty stuff (which may or may not be true), George Robert Elford, Devil's Guard (from the early 1970s, with I believe a couple of sequels I don't have) - SS officer who served in Vietnam with a Legion German unit he commanded. Whether fact or fiction, it is an interesting read.
Actually it is true that many of the foreign legion after WW2 were german. The fact they were SS is doubtful as they all were rewarded as war criminals at that time and Legion Etrangere as a quite strict code on that issue. But I do not know if it was in place or implemented at that time. France was desperate to find fighters for Indochina.

Just for the fun and having some feelings on the context I would recommand also to watch Indochina and Bien Dien Phu.
The first one is not a war movie but gives a good idea of what was the the atmosphere in Indo at the time. The seccond one is all about the Bien Dien Phu battle.

Good luck Kevin