French Colonies. (Camerouns). 1917. Stamp-less envelope headed 'Service Militaire' addressed to the 'Commandant 18th Battalion Indochinese, Fort de Vincennes, France' Cancelled by Duala/Cameroon double ring '31st Juil 17' with hand-struck 'Le Colonel Thomassen /Commadant Militaire du Cameroun/P.O. l' Officier Adjoint' and signed by the Commandant Militaire with circular 'Cameroun/ Le Commandant Militaire'. Very fine.