I’ve only seen one other of these in 30 years.  It is the rarest martial Colt and the hardest to find.  The" Union Defense Committee " was an arm of the US Navy. They purchased 50 of these pistols for naval use during the Civil War . There are only 9 of them known to exist today. This gun has all matching serial numbers except the loading lever.  I’ll let the pictures speak for themselves. 
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