2nd Missouri Cavalry Regiment (Union)

The 2nd Missouri Cavalry Regiment, also known officially as Merrill's Horse,^[1] was a cavalry regiment that served in the Union Army during the American Civil War. The regiment was one of only a handful of Missouri regiments to be officially named as well as numbered.

The regiment was raised under the authority of Major General John C. Frémont, commander of the Western Department of the U.S. Army, headquartered at St. Louis, Missouri. The regiment was organized by Captain Lewis Merrill, a regular Army officer and a veteran of the prewar U.S. 2nd Dragoons. Serving as a colonel of volunteers, Merrill organized companies of volunteers from Missouri and other western states at St. Louis's Benton Barracks. Merrill enforced a level of discipline unusual for volunteer regiments, demanding a level of professionalism comparable to U.S. Regulars.

To distinguish the troops of his regiment, Merrill mandated a unique uniform. The front of the tunic featured a "horse-head" panel trimmed in cavalry yellow. The mandated cap was similarly unique: a sky-blue forage cap, with an orange welt (the branch color of pre-war Dragoon regiments) in honor of Merrill's service in the 2nd Dragoons. As with other areas of military discipline, Merrill allowed no deviation from his orders to his troopers in concerning their military appearance: "all additions to or alterations of this uniform as prescribed are positively prohibited and will not be tolerated under any circumstances."

Through most of 1862, Merrill's Horse was assigned the difficult mission of fighting guerrillas and irregular Confederate cavalry in north Missouri. Often operating with Federal Missouri State Militia cavalry, the regiment established a reputation of extreme aggressiveness and effectiveness in the counter-guerrilla mission. Later in the war Merrill's Horse would provide distinguished service in more conventional cavalry missions against regular Confederate units. However, in Arkansas, Tennessee, Georgia, and Alabama the regiment was repeatedly called on to return to the difficult specialist counterinsurgency mission of guerrilla fighting.

The regiment is unusual in that it has two official designation. It was officially raised as "Merrill's Horse", and is usually referred to by that designation in period U.S. Army Records. However, after General Fremont was replaced as commander of the Western Department by Major General Henry Halleck received a second official designation at the 2nd Missouri Volunteer Cavalry.^[2] However, in almost all contemporary reports and records the regiment continued to be referred to as Merrill's Horse.