Trans-Mississippi Theater of the American Civil War
Years: 1861 - 1865
The Trans-Mississippi Theater of the American Civil War consists of the major military operations west of the Mississippi River.
Activity in this theater in 1861 is dominated largely by the dispute over the status of the border state of Missouri.
The Missouri State Guard, allied with the Confederacy, wins important victories at the Battle of Wilson's Creek and the First Battle of Lexington.
However, they are driven back at the First Battle of Springfield.
A Union army under Samuel Ryan Curtis defeats the Confederate forces at the Battle of Pea Ridge in northwest Arkansas in March 1862, solidifying Union control over most of Missouri.
The areas of Missouri, Kansas, and the Indian Territory (modern-day Oklahoma) are marked by extensive guerrilla activity throughout the rest of the war, the most well-known incident being the infamous Lawrence massacre in the Unionist town of Lawrence, Kansas of August 1863.
In the spring of 1862, Confederate forces push north along the Rio Grande River from El Paso, Texas through the New Mexico Territory, but are stopped at the Battle of Glorieta Pass (March 26-28, 1862).
In 1863, General Edmund Kirby Smith takes command of the Confederate Trans-Mississippi Department, and unsuccessfully tries to relieve the Siege of Vicksburg by Lt. Gen. Ulysses S. Grant on the opposite eastern banks of the Mississippi River in the state of Mississippi.
As a result of the long campaign / siege and surrender in July 1863 by Gen. John C. Pemberton, the Union gains control of the entire Mississippi River, splitting the Confederacy.
This leaves the Trans-Mississippi Department almost completely isolated from the rest of the Confederate States to the east
It becomes nicknamed and known as "Kirby Smithdom", emphasizing the Confederate Government's lack of direct control over the region.
In the 1864 Red River Campaign, a U.S. force under Major General Nathaniel P. Banks tries to gain control over northwestern Louisiana, but is thwarted by Confederate troops commanded by Richard Taylor.
Price's Raid, an attempt led by Major General Sterling Price to recapture Missouri for the Confederacy, ends when Price's troops are defeated in the Battle of Westport that October.
On June 2, 1865, after all other major Confederate armies in the field to the east have surrendered, Kirby Smith officially surrenders his command in Galveston, Texas.
On June 23, Stand Watie, who commands Southern troops in the Indian Territory, becomes the last Confederate general to surrender.