The 9th Missouri State Militia Cavalry, was a cavalry regiment that served as an element of the Union Army in the state of Missouri during the American Civil War. Unlike Militia units in other states, the 9th Missouri State Militia Cavalry was a full-time military unit, permanently engaged in internal counter-insurgency and protection of the state of Missouri from invasion by conventional Confederate units. The regiment was equipped and paid by the Federal government and was integrated into the Federal military structure in the Department of Missouri. The 9th MSM Cavalry was one of Missouri's most successful counter-guerrilla units.