The Transmississippi Theater of the American Civil War covered the area of the United States between the Mississippi River and the Pacific Ocean. Most major battles in this theater were fought in Missouri, Arkansas, Kansas, and Louisiana, while smaller battles and skirmishes were fought in Oklahoma, Texas, and New Mexico.

War on the Frontier: The Trans-Mississippi West
Battle of Carthage, Missouri: First Trans-Mississippi Conflict of the Civil War
The Battle of Glorieta Pass: A Gettysburg in the West, March 26-28, 1862
The Two Civil War Battles of Newtonia: Fierce and Furious
The Battle of Carthage: Border War in Southwest Missouri, July 5, 1861
The War in the Far West: 1861-1865
Campaign for Wilson’s Creek: The Fight for Missouri Begins
Soldiers in the Army of Freedom: The 1st Kansas Colored, the Civil War's First African American Combat Unit
The Yankee Invasion of Texas
General Jo Shelby: Undefeated Rebel
The Confederate Cherokees: John Drew's Regiment of Mounted Rifles
The Battle of Mine Creek: The Crushing End of the Missouri Campaign
Pea Ridge: Civil War Campaign in the West
October 25th and the Battle of Mine Creek
A Crisis in Confederate Command: Edmund Kirby Smith, Richard Taylor, and the Army of the Trans-Mississippi