O 1/7 OC. 88" squared circle d.s., showing "POSTAGE DUE/1 ANNA" h.s. and arrival c.d.s. (on reverse). Military mail posted during this obscure conflict is extremely rare. Photo" /> cover 1888 (7 Oct.) underpaid ½a. green stationery envelope to Abbottabad cancelled by a fair to good strike of the "FIELD P.O. N<V>O 1/7 OC. 88" squared circle d.s., showing "POSTAGE DUE/1 ANNA" h.s. and arrival c.d.s. (on reverse). Military mail posted during this obscure conflict is extremely rare. Photo | Christie's