William P. Uhlinger produced about 10,000 rimfire cartridge revolvers (two types in .22 caliber and one type in .32 caliber) in Philadelphia, PA between 1861 and 1865. He had purchased the tools and parts on hand of William Hankins, who had left his former gun making business behind to form a new venture with Sharps rifle inventor Christian Sharps, thus forming the firm of Sharps & Hankins.
Since the guns that Uhlinger was producing were revolvers with bored through cylinders, he was in violation of the Rollin White Patent, which was held by Smith & Wesson. As a result Uhlinger produced the guns under a variety of trade names such as WL Grant, JP Lower and DD Cone in an attempt to conceal the identity of actual manufacturer, and avoid any legal troubles. About 50% of his pistols were also manufactured with no markings at all. He assumed this would help to avoid detection of his patent violations by Smith & Wesson, but it did not. He was eventually sued by Smith & Wesson for patent violations, and they won the case handily. The suit essentially put Uhlinger out of the gun business, and resulted in his gun being an interesting footnote in firearms history.
Considering the time and production totals one has to assume they were well accepted, no doubt that many a Union soldier went to war with a small frame Uhlinger .22 RF pistol in his pocket for emergencies. More than likely many line officers probably found the robust design of his solid frame .32 RF pistol as a much sturdier choice for their personal defense than the Smith & Wesson #2 Old Army revolver.
Note the ejector rod under the barrel. The rod has a stationary pin on one end and a spring-loaded pin on the other end. It snaps into place between the rod stop at the end of the barrel and the frame in front of the cylinder. Rather unique and inexpensive arrangement.
This one is marked with: "J. P. LOWER" on the top of the barrel. Lower was a clerk for arms dealer J. P. Grubb in Philadelphia.