The Red River campaign or Red River expedition comprised a series of battles fought along the Red River in Louisiana during the American Civil War from March 10 to May 22, 1864. The campaign was a Union initiative, fought between approximately 30,000 Union troops under the command of Major General Nathaniel P. Banks, and Confederate troops under the command of Lieutenant General Richard Taylor, whose strength varied from 6,000 to 15,000.

The campaign was primarily the plan of Union General-in-Chief Henry W. Halleck, and a diversion from Lieutenant General Ulysses S. Grant's plan to surround the main Confederate armies by using Banks's Army of the Gulf to capture Mobile, Alabama. It was a Union failure, characterized by poor planning and mismanagement, in which not a single objective was fully accomplished. Taylor successfully defended the Red River Valley with a smaller force. However, the decision of Taylor's immediate superior, General Edmund Kirby Smith, to send half of Taylor's force north to Arkansas rather than south in pursuit of the retreating Banks after the Battle of Mansfield and the Battle of Pleasant Hill, led to bitter enmity between Taylor and Smith.

Union

The Union forces consisted of four elements, the first three of which worked together:

1. Troops from the Department of the Gulf, commanded by Major General Banks, consisting of two infantry divisions from the XIII Corps, two infantry divisions from the XIX Corps, a cavalry division, and a brigade of US Colored Troops, in total approximately 20,000 men.
2. 10,000 men from XVI Corps and XVII Corps from the Army of the Tennessee under A.J. Smith.
3. The Mississippi flotilla of the US Navy, commanded by Admiral Porter, consisting of ten ironclads, three monitors, eleven tinclads, one timberclad, one ram, and numerous support vessels.
4. 7,000 men under General Steele in the Department of Arkansas.

Confederate

Confederate forces consisted of elements from the Trans-Mississippi Department, commanded by E. Kirby Smith.

1. The District of West Louisiana, commanded by Richard Taylor, contained approximately 10,000 men, consisting of two infantry divisions, two cavalry brigades and the garrison of Shreveport.
2. The District of Arkansas, commanded by Sterling Price, contained approximately 11,000 men, consisting of three infantry divisions and a cavalry division. As the campaign began, Smith ordered two of Price's infantry divisions to move to Louisiana.
3. The District of Indian Territory (Oklahoma), commanded by Samuel Maxey, contained approximately 4,000 men in three cavalry brigades.
4. The District of Texas, commanded by John Magruder, 15,000 men, mostly cavalry. As the campaign began, Smith ordered Magruder to send as many men as he could. Over the course of the campaign almost 8,000 cavalry came from Texas to aid Taylor in Louisiana; however, it arrived slowly and not all together.
5. The Confederate Navy based in Shreveport had the ironclad CSS Missouri, the gunboat Cotton, and the ram CSS Webb.

Battles

1. Battle of Mansfield
2. Battle of Pleasant Hill
3. Battle of Balir's Landing
4. Battle of Yellow Bayou
5. Battle of Fort De Russy
6. Battle of Mansura

The Red River Campaign was a Union failure, the outcome of which did not have a major impact on the war. Conversely, it may have extended the length of the war by several months, as it diverted Union efforts from the far more important objective of capturing Mobile, Alabama.

The failure of the campaign effectively ended the military career of Banks, and controversy surrounding his retreat, the presence of cotton speculators and the use of military boats to remove cotton dogged his early postbellum congressional campaigns. Admiral Porter realized a substantial sum of money during the campaign from the sale of cotton as prizes of war.

The Confederates lost two key commanders, Mouton and Green, and suffered casualties they could not afford. Perhaps more importantly, relations between the aggressive Taylor and cautious Smith were permanently damaged by their disagreement over Smith's decision to remove half of Taylor's troops following the Battle of Pleasant Hill. The lost opportunity to capture the entire Union fleet as it lay helpless above the falls at Alexandria haunted Taylor to his dying day; he was certain that Smith had robbed him a chance to cripple the Union forces. The arguments between the two generals resulted in Taylor's transfer to command of the Department of East Louisiana, Mississippi, and Alabama soon after the campaign ended.