Military post offices on the Salonica front. Cover fr. with 3x10c. and posted from "TRESOR ET POSTES*504*26 1 17" with Serbian censorships "OUVERT PAR LAUTORITE/MILITAIRE SERBE" and "CORRESPONDANCES MILITAIRES", these 2 censor marks were used from "Chief Censor Office". The precise role is unclear. Only 1 is censor marking, the other is merely informational. Also French Censorship "OUVERT par l"AUTORITE*101", arr. "WEESEN*11.III.17".