The Merrill carbine was one of the many inventive breechloaders developed at the start of the Civil War, when the U.S. government was scrambling to arm a rapidly expanding cavalry. Designed by Baltimore gunsmith James H. Merrill, it was patented in 1858 and produced mainly by Merrill, Latrobe & Thomas in Baltimore, Maryland. Merrill’s goal was to build a simple, sturdy carbine that could be loaded from the breech rather than the muzzle — something soldiers could reload quickly on horseback without fumbling with powder and ball.

The carbine used a plunger-style breech lever that locks tight when closed and fires a .54 caliber paper cartridge. It was made in two main variations: the early “First Type” with a brass patch box and the later “Second Type” with iron mounts and minor improvements to the breech mechanism. Merrill’s design wasn’t as fast as a Spencer or Henry repeater, but it was reliable, weather-resistant, and far easier to load than traditional muzzleloaders.

The Merrill was widely issued to Union cavalry units, particularly those from border states and the mid-Atlantic region. Regiments such as the 1st, 5th, and 18th New York Cavalry, the 1st and 3rd Wisconsin Cavalry, and the 7th Indiana Cavalry were all known to carry them. They saw service in major campaigns and battles across the eastern and western theaters — including Gettysburg, Antietam, Vicksburg, and the Shenandoah Valley operations.

Roughly 14,500 Merrill carbines were made, and despite competition from other designs, it earned a solid reputation for ruggedness and dependability in the field. Cavalrymen liked that it was simple to maintain and could fire accurately even after hard use. While it was eventually overshadowed by repeating carbines later in the war, the Merrill served faithfully through the conflict and remained a dependable symbol of the early shift toward modern breechloading arms.