British WWI military mail in Egypt: 15 VI 1917 stampless (OAS) civilian stationary cover from CAIRO to BOGNOR, tied by CAIRO-K postmark on earliest known date of use in EEF period & with officer's signature; backstamped next day APO SZ 10 (Cairo) transit using large Proud-D7 postmark, opened & resealed by censor; opened at back, tear to flap, complete. Unusual local routing from civilian to military post as most of the period military mail for abroad received by the civilian post office was not marked by a British military post office subsequent to overseas dispatch (although those marked like this generally originated from Cairo).