This is a scarce example of a U.S. martially marked Colt Model 1855 revolving rifle. The Ordnance Department purchased 4,613 Colt 1855 Military Rifles during the Civil War; nearly 900 of these rifles were purchased from B. Kittredge and other commercial sources and over 3,700 rifles were purchased directly from Colt. The 1st and 2nd U.S. Sharpshooters (Berdan's Sharpshooters), the 21st Ohio Infantry and 2nd Michigan Cavalry were primarily armed with Colt Model 1855 Military Rifles. The rifle has a five-shot cylinder, a Root-type side hammer, ratchet-type loading lever, and is fitted with a block front sight base which serves as a mount for an angular socket bayonet. The folding three leaf rear sight is graduated for 100, 300 and 600 yards. The rifle has an iron cleaning rod with knurled handle and threaded end fitted in the forearm. "COLTS/PATENT/US" visible on the top strap with illegible patent markings. Illegible boxed script cartouche on the left wrist, and "WAT" (William A. Thornton) on the right. "56 CAL" marked on the left side of the trigger guard bow. Small "K" inspector stamp on the left breech end of the barrel and left sideplate. All matching serial numbers "977" marked on the barrel beneath the forearm, in the forearm channel, trigger guard tang, and toe of the buttplate. The stock and forearm are black walnut with a varnish finish. Factory sling swivels are located on the middle barrel band and trigger guard tang. The buttplate has a sliding trap door. Includes "U.S." marked socket bayonet and leather scabbard.