The Red River Campaign was a major Union offensive campaign in the Trans-Mississippi theater of the American Civil War, which took place from March 10 to May 22, 1864. It was launched through the densely forested gulf coastal plain region between the Red River Valley and central Arkansas towards the end of the war. Union strategists in Washington thought that the occupation of east Texas and control of the Red River would separate Texas from the rest of the Confederacy. Texas was the source of much needed guns, food, and supplies for Confederate troops. The Union had four goals at the start of the campaign:

1. Capture of Shreveport, the state capitol and headquarters of the Trans-Mississippi Department.
2. Destroy Confederate forces in the District of West Louisiana commanded by General Richard Taylor.
3. Confiscate as much as a hundred thousand bales of cotton from the plantations along Red River.
4. Organize 'pro-Union' state governments throughout the region under Lincoln's "ten percent" plan.

The expedition was a Union military operation, fought between approximately 30,000 federal troops under the command of Major-General Nathaniel P. Banks, and Confederate forces under General E. Kirby Smith, whose strength varied from 6,000 to 15,000. The Battle of Mansfield was a major part of the Union offensive campaign, which ended in defeat for General Banks.

The expedition was primarily the plan of Major-General Henry W. Halleck, former General-in-Chief of the Armies of the United States, 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. It was a total failure, characterized by poor planning and mismanagement, in which not a single objective was fully accomplished. Major-General Richard Taylor successfully defended the Red River Valley with a smaller force. However, the decision of his immediate superior, Kirby Smith, to send half of his force north to Arkansas rather than south in pursuit of Banks after the battles of Mansfield and Pleasant Hill, led to bitter enmity between Taylor and Smith.