CASTLE THUNDER, RICHMOND, VA: prisoner-of-war cover postmarked OLD POINT COMFORT, VA. OCT 24 double-circle datestamp with DUE 6 to Windham, Conn., from civilian hostage Charles Thompson to his wife. He was interned at Castle Thunder. Included is a printed Provost Marshal's civilian pass through the lines from the Military Governor at Norfolk, Va., datelined "Norfolk, Va. May 14th, 1863." Click here to see back of Provost Marshal's pass.  Cover is exceptionally clean and attractive, the pass is folded and slightly rough around the edges as one would expect from something kept in his pocket. ONE OF ONLY 11 COVERS RECORDED BY HARRISON. Rare with a military pass. Thompson sent the Union pass to his wife in the cover as a souvenir. He was carrying it when he was captured on the mail steamer to Roanoke Island, signed by Thompson swearing he will "give no aid, comfort, nor information to enemies of the United States Government." Ex Harrison and mounted on his award-winning exhibit page. LL $1,000.