Union Prisoner-of-War Cover
The envelope, postmarked Delaware City, Delaware, August 9, 1864, bears a Federal prison mark, indicating examination of the prisoner's letter. A concentric circle killer was used to cancel the postage stamp.
Federal prisons, like Fort Delaware located off the coast of Delaware City, required Confederate prisoners to adhere to special rules in regard to their letters. A prisoner's letter had to be enclosed in an unsealed envelope and placed in an outer envelope. It was then sent to a designated location, where the outer envelope was opened, destroyed, and the enclosed letter was examined. If approved, the letter was sealed, marked 'Examined', and placed in the mail at a nearby post office.