Military post offices on the Salolica front. French Aviation Mission with the Serbian army, 4-line marking. Cover with French Unit marking "Aviation Militaire Francaise/Aupres de lArmee Serbe/ESCADRILLE F.82S/Secteur Postal 504", posted from "TRESOR ET POSTES-504*10.9.16", arr. "ST.VALERY EN CAUX*17.9.16".