The Trans-Mississippi Theater Campaign of the Civil War was the major military and naval operation west of the Mississippi River, with the exception of those near the Pacific Coast. The Confederate Trans-Mississippi Department was formed on May 26, 1862, after recognizing problems associated with trying to govern a region more than a thousand miles distant from the capital at Richmond, Virginia. The area included Missouri, Arkansas, Texas, Indian Territory (Oklahoma), and Louisiana west of the Mississippi River.

Until the surrender of Vicksburg, Mississippi, the Trans-Mississippi region offered many important resources, including significant numbers of men, Texas cattle, war goods from Mexico, and Texas and Louisiana cotton. Additionally, the small Army of the Trans-Mississippi the Union to keep a military presence in the region, thus tying up men who could have been used elsewhere.

After the summer of 1863, Arkansas, Louisiana, and Texas no longer made a significant contribution to the Confederacy. As a result, the states along the east bank of the Mississippi River suffered too. Tennessee, with its capital under Union control, could offer little to the Confederate war effort but men. Even within the Army of Tennessee, Trans-Mississippi Confederates from Texas occasionally deserted to go home to protect family and friends from marauding Indians. By ignoring the needs of the western Confederacy, and allowing the isolation of the Trans-Mississippi, Confederate President Jefferson Davis forced leaders in the region to rely on their own resources and manpower. Both politicians and military commanders knew that by 1864 the region’s inhabitants had become less willing to send their soldiers elsewhere and that many soldiers would refuse to go. It is true that Trans-Mississippians failed to provide the needed diversions for the fighting in late 1864 and as a result A. J. Smith helped destroy John B. Hood’s army at the Battle of Nashville, but the failure of Confederate leaders to see the Trans-Mississippi as an asset in 1861, or even as a source of manpower to protect the Mississippi River Valley in Arkansas and Louisiana early in the war, ranks as one of the major failures of Confederate strategic thinking. It can also be argued that the manpower to cover all the states from the Carolinas to Texas was simply not there, and when Davis set his priorities, he decided to sacrifice the Trans-Mississippi in order to use the soldiers to defend important cities in the Western Theater.

Yet this decision fostered resentment and frustration among Confederates west of the river. Once Vicksburg, Mississippi fell and the Trans-Mississippi became a semi-independent department, the region’s leaders, both civilian and military, made no concentrated attempt to aid the overall war effort and essentially ignored Jefferson Davis’s plea of “one cause, one country” fighting together “for the defense of each other.” As a result, the Union ultimately proved more successful at combining its resources on both sides of the river, while the Confederacy maintained two distinct areas of operations west of the Appalachian Mountains—uncoordinated and separated—to the end.

Operations to Control Missouri, June-October 1861

Boonville, Missouri – June 17, 1861
Carthage, Missouri – July 5, 1861
Wilson’s Creek, Missouri – August 10, 1861
Dry Wood Creek, Missouri – September 2, 1861
Lexington, Missouri – September 13-20, 1861
Liberty or Blue Mills, Missouri – September 17, 1861
Fredericktown, Missouri – October 21, 1861
Springfield, Missouri – October 25, 1861

Operations in the Indian Territory – November-December 1861

Round Mountain, Oklahoma
Chusto-Talasah, Oklahoma
Chustenahlah, Oklahoma

Operations in Northeast Missouri – December 1861

Mount. Zion Church, Missouri
Roan’s Tan Yard, Missouri

Sibley’s New Mexico Campaign – February-March 1862

Valverde, New Mexico
Glorieta Pass, New Mexico

Pea Ridge Campaign – March 1862

Pea Ridge, Arkansas

Operations on the White River – June 1862

Saint Charles, Arkansas

Operations Near Cache River – July 1862

Hill’s Plantation, Arkansas

Operations North of Boston Mountains – August-November 1862

Clark’s Mill, Missouri
Kirksville, Missouri
Independence, Missouri
Lone Jack, Missouri
Newtonia, Missouri
Old Fort Wayne, Oklahoma

Operations to Suppress the Sioux Uprising – August-September 1862

Fort Ridgely, Minnesota
Wood Lake, Minnesota

Operations to Blockade the Texas Coast – September 1862-January 1863

Sabine Pass, Texas
Galveston, Texas

Prairie Grove Campaign – November 1862

Cane Hill, Arkansas
Prairie Grove, Arkansas

Operations Against Galveston – December 1862-January 1863

Galveston, Texas

Marmaduke’s First Expedition into Missouri – January 1863

Springfield, Missouri
Hartville, Missouri

Marmaduke’s Second Expedition into Missouri – April-May 1863

Cape Girardeau, Missouri
Chalk Bluff, Arkansas

Operations to Control Indian Territory – June-September 1863

Cabin Creek, Oklahoma
Honey Springs, Arkansas
Devil’s Backbone , Arkansas

Quantrill’s Raid into Kansas – August 1863

Lawrence, Kansas

Operations to Blockade the Texas Coast – September 1863

Sabine Pass II, Texas

Advance on Little Rock – September-October 1863

Bayou Fourche, Arkansas
Pine Bluff, Arkansas

Occupation of Indian Territory North of the Arkansas River – October 1863

Baxter Springs, Kansas

Red River Campaign – March-April 1864

Fort De Russy, Louisiana
Mansfield, Louisiana
Pleasant Hill, Louisiana
Blair’s Landing, Louisiana
Monett’s Ferry, Louisiana
Mansura, Louisiana
Yellow Bayou, Louisiana

Camden Expedition – April 1864

Elkin’s Ferry, Arkansas
Prairie D’Ane, Arkansas
Poison Spring, Arkansas
Marks’ Mills, Arkansas
Jenkin’s Ferry, Arkansas

Expedition to Lake Village – June 1864

Old River Lake, Arkansas

Price’s Missouri Expedition – September-October 1864

Fort Davidson, Missouri
Glasgow, Missouri
Lexington, Missouri
Little Blue River, Missouri
Independence, Missouri
Byram’s Ford, Missouri
Westport, Missouri
Marais des Cygnes, (Kansas)
Marmiton River, Missouri
Mine Creek, Kansas
Newtonia, Missouri

Expedition from Brazos Santiago – May 1865

Palmeto Ranch, Texas

Compiled and edited by Kathy Alexander/Legends of America, updated December 2021.

Also See:

Causes of the Civil War

The Civil War

Civil War Photo Galleries

Timeline & Leading Events