The picture of Captain Brown's cover or envelope postmarked Oct.5,1864 at Charleston is in,"The Confederate States of America.The Special Postal Routes" by Lawrence L.Shenfield.The Collectors Club,New York,1961.p49
Obviously while a prisoner at Morris Island Captain Brown wrote his father a letter then at Brown's Cove,Albemarle Co.,Va.Unfortunately the contents of the letter are not mentioned.
Some few other soldiers covers are shown in the article.In particular Colonel William H.Forney,10th.Alabama,one of the 50 prisoners sent to Hilton Head in June 1864.Colonel Forney is writting a Mrs.Eliza Forney at Jacksonville,Alabama.
In addition Major T.E.Upshaw,13th Virginia Cavalry written July 7,1864.while aboard the prison ship off Hilton Head.A portion of the letter enclosed is mentioned,"Have been sent here with 49 other officers of the C.S,Army as hostages for the safety of certain Federal officers held by Major general Sam Jones in Charleston,SC supposed to be in danger." Major Upshaw is writting a lady Near Charlottesville,Va.
Mike