the campaigns and battles of the American Civil War that were fought for control of the Mississippi River. Western waterways were major arteries of communication and commerce for the South, as well as a vital link to the Confederate states of Louisiana and Texas. Early in the war, Union strategists settled on the Mississippi and tributary rivers such as the Cumberland and Tennessee as proper avenues of attack. In addition to the fighting along the Richmond, Virginia–Washington, D.C., axis, the campaign for Atlanta (Atlanta Campaign), Georgia, and General William Sherman (Sherman, William Tecumseh)'s March to the Sea, the struggles for western rivers constituted the major battles of the Civil War.

The West's vast expanse complicated Confederate defense of the region, a problem first obvious at the Battles of Fort Henry (Fort Henry, Battle of) and Fort Donelson (Fort Donelson, Battle of) in February 1862. After these forts fell to Union troops, Nashville, Tennessee, was evacuated, and the way to Atlanta was clearer for Federal troops later in the war. The Battle of Shiloh (Shiloh, Battle of), fought on April 6 and 7, 1862, farther down the Tennessee River from Fort Henry, was up to that point the biggest battle in American history. It pitted more than 100,000 men in armed struggle near a steamboat docking point called Pittsburg Landing and presented a preview of the terrible carnage that was to come at places such as Antietam (Antietam, Battle of) and Gettysburg (Gettysburg, Battle of); after the North won the battle, each side counted more than 1,700 dead and 8,000 wounded. The Battle of Shiloh preserved an important Union flank along the Mississippi River and opened the way to split the Confederacy along the river. In May and June of 1863 Union General Ulysses S. Grant (Grant, Ulysses S.) marched on Vicksburg (Vicksburg Campaign), Mississippi, and trapped a Southern army led by General John Pemberton (Pemberton, John Clifford). After a brilliant joint operation using land and naval forces, Vicksburg fell to the Federals on July 4. With the capture of the city, the Union not only gained control of the lower Mississippi, its outlet to the Gulf of Mexico, but also effectively cut the South in two.

Later in the war a smaller campaign along a western tributary, the Red River, consolidated Union control of the Mississippi basin and helped seal the Confederate fate. Altogether, Americans fought at least 26 named battles and innumerable skirmishes along western waterways. The contests for these rivers were a critical cog in Northern strategy and helped produce some of the war's greatest personalities, including Generals Grant and Sherman.