The 1st Missouri Cavalry Regiment fought at the Battle of Pea Ridge, Arkansas from March 6–8, 1862, then moved east of the Mississippi River and was dismounted. On May 4, 1862, the regiment contained 536 effectives. After fighting at the Battle of Iuka, Mississippi on September 19, 1862, the regiment participated in the Battle of Corinth, Mississippi on October 3–4, 1862, where it lost 9 killed and 54 wounded. It was then assigned to Martin E. Green's Brigade, Department of Mississippi and East Louisiana. The regiment fought at the Battle of Champion Hill, Mississippi on May 16, 1863, and took an active part in the Battle of Big Black River Bridge on May 17. On July 4, 1863, it surrendered at the end of the Siege of Vicksburg. After being paroled, the regiment was declared exchanged on September 12, 1863. It was assigned to General Cockrell's Missouri Brigade, and consolidated with the 3rd (Samuel's) Missouri Cavalry Battalion. The 1st/3rd Battalion fought with the Army of Tennessee throughout the Atlanta Campaign and reported 25 killed, 80 wounded, and 3 missing at its end. On October 5, 1864 the battalion saw action in the Battle of Allatoona, Georgia, where it sustained 56 casualties. In late 1864, it was part of Hood's operations in Tennessee, and fought at the Battle of Franklin on November 30. Later it was involved in the defense of Mobile, Alabama, fighting at the Battle of Fort Blakely, Alabama from April 2–9, 1865. The small command surrendered with the Department of Alabama, Mississippi, and East Louisiana, and was disbanded on May 13, 1865.