It appears that Gilbert Bourgeaud or "Bob Denard" may have been part of Katanga militias in the "Siege of Jadotville" (now also a film from Netflix).

A militia force of about 3000 laid siege to about 156 Irish UN troops, who held out for 5 days before surrendering.

https://en.wikipedia.org/wiki/Siege_of_Jadotville

https://en.wikipedia.org/wiki/Roger_Faulques#Congo_Crisis

https://en.wikipedia.org/wiki/Bob_Denard#Early_career

It's hard to confirm if he was there, Roger Faulques his friend and leader of the militia force certainly was.