cover 12c Black (17), horizontal strip of three, clear to huge margins except slightly in at top of left stamp, used with single 1c Blue type IV (9), large margins to cut in, all tied by clear "Davenport, Ioa. Apr 16" c.d.s. cancels on 1855 buff cover to Holstein, (Denmark) (while the cover is addressed to "Germany", Holstein was actually part of Denmark at this time and control of Holstein was very intensely disputed between Germany and Denmark), red "N.York Br. Pkt. 7 Paid Apr 24" exchange h.s., red "Franco Pruess:/resp. Vereins Ausg Gr" boxed h.s. (paid to the German-Austrian Postal Union border), Aachen, Hamburg and Royal Danish Postal Agency-Hamburg backstamps, from the German-Austrian border the letter was treated as unpaid and charged "9" (skillings) Danish postage due from the recipient, carried by the Cunard Line steamer America, this cover paid the 37c rate to Denmark via Prussian Closed Mail (a rate in effect until July of 1855), cover faults and opened on couple sides, otherwise fine, a unique 1851 Issue usage to Denmark, a fabulous rarity worthy of the very finest collection photo