MARINE HOSPITAL, CHARLESTON, S.C., UNION 600: cover to Wm H. Durfee, Newport, R.I. from Wm. McDurfee, Lt., Co. A, 5th R.I. Art., Prisoner of War, Charleston, R.I. at upper left; entered U.S. mails with PORT ROYAL, S.C. OCT. 6, 1864 double-circle postmark and Due 3 handstamp; manuscript endorsement Stewart L. Woodford, Lt. Col. & Agent for Exchange at left with manuscript censor "Exd" (by Hugh Hamilton Rogers) and additional light pencil notation "Ex" at right, receiving "Newport, R.I. Oct. 17, '64" double circle postmark, slightly reduced at right, Very Fine and rare, ex Walske and Harrison. THIS IS ONE OFONLY 3 COVERS ARE RECORDED by prior owner Galen Harrison. AN OUTSTANDING PRISON OF WAR COVER FROM THIS SMALL HOSPITAL USED BRIEFLY TO HOUSE FEDERAL OFFICERS. Many of Union officers held here, made up in part the famous "Charleston 600" held under fire of their own guns on Morris Island. $2,000.