Air mail fees on FM

Up to Independence in 1956, French forces in Tunisia had to pay the extra airmail fee on Franchise Militaire mail.

From 1956-1963 (when the French finally left) my 5 "Par Avion" samples show no air mail fee paid.

Does any member know if the requirement to pay was withdrawn or simply not applied?

I cannot find the answer in the books by Picrilli or Richardson.
Derek Richardson has kindly drawn my attention to

Alexandre et al Les Tarifs Postaux Francais 1627-1969
Pages 177-188 contain “Tarifs et Franchises pour les militaires en campagne, 1854-1964”

but even this does not answer my question!
Where do I go from here?
Thanks
DHT

There was an article in a recent copy of Timbres regarding the franchise and the air surtax. Apparently after liberation for mail between military personnel both from and to a French controlled terrritory then no surtax applied. If one or other was non French then the franchise applied for the basic foreign rate but the air surtax was due. Arguments about the post office incorrectly trying to charge a surtax not actually due led to complaints. So between French territories full franchise should be accepted including air mail. I would imagine confusion and incorrect practice extended into the 1950s

MANY THANKS, Chris. That is just what the evidence suggested.
David