Provisional Government of Missouri
The Provisional Government of Missouri was established on August 1, 1861 by the members of the Missouri Constitutional Convention after the evacuation of Missouri's pro-Secessionist Governor Clairborne Fox Jackson and elements of the Legislature to the southern part of the state. The Missouri State Convention, acting under authorities granted to it by the special election earlier that year, declared the office of Governor vacant, and appointed former Missouri Supreme Court Justice Hamilton Gamble Governor. Even opponents of Federal action in Missouri generally respected Gamble.
Military
The Provisional Government of Missouri, faced a difficult task, dealing with Missouri secessionists who considered Union men traitors, and Federal troops from outside the state who tended to view all Missourians as potential rebels.
Governor Gamble convinced President Lincoln that local units composed of Missourian, controlled by the (Provisional) State Government, would be the least disruptive way to deal with Missouri Guerrillas and would free out-state Federal regiments for other combat roles. This lead Lincoln to authorized the creation of the (new) Missouri State Militia, a military force with a legal status unique in U.S. history. It was paid and equipped by the Federal government, but ultimately reported the Governor of Missouri, and had a service obligation limited to Missouri, and operations related to Missouri security. To integrate the MSM with federal forces in the region Governor Gamble commissioned Major General Henry W. Halleck, the Federal commander of the Department of the Mississippi as the Major General of the Missouri State Militia.
The Missouri State Militia, and the later Enrolled Militia and Provisional Enrolled Militia, did not fully suppress guerrilla activity in the state (neither could conventional Federal troops) but did contribute significant combat power (directly and indirectly) to Federal efforts in the Trans-Mississippi Theater Trans-Mississippi Theater.
Due to its internecine nature, the Civil War in Missouri would be longer and more brutal than anywhere else in the U.S. However, the Provisional Government managed to keep the majority of Missourians from embracing secessionism, and played a vital role in holding the state for the Union.