American Civil War: General Ulysses S. Grant captures Fort Donelson, Tennessee.

The American Civil War was a civil war in the United States between the Union and the Confederacy, which was formed in 1861 by states that had seceded from the Union. The central conflict leading to war was a dispute over whether slavery should be permitted to expand into the western territories, leading to more slave states, or be prohibited from doing so, which many believed would place slavery on a course of ultimate extinction.

Ulysses S. Grant was the 18th president of the United States, serving from 1869 to 1877. In 1865, as commanding general, Grant led the Union Army to victory in the American Civil War.

The Battle of Fort Donelson was fought from February 11–16, 1862, in the Western Theater of the American Civil War. The Union capture of the Confederate fort near the Tennessee–Kentucky border opened the Cumberland River, an important avenue for the invasion of the South. The Union's success also elevated Brig. Gen. Ulysses S. Grant from an obscure and largely unproven leader to the rank of major general, and earned him the nickname of "Unconditional Surrender" Grant.

Fort Donelson was a fortress built early in 1862 by the Confederacy during the American Civil War to control the Cumberland River, which led to the heart of Tennessee, and thereby the Confederacy. The fort was named after Confederate general Daniel S. Donelson.

Tennessee, officially the State of Tennessee, is a landlocked state in the Southeastern region of the United States. It borders Kentucky to the north, Virginia to the northeast, North Carolina to the east, Georgia, Alabama, and Mississippi to the south, Arkansas to the southwest, and Missouri to the northwest. Tennessee is the 36th-largest by area and the 15th-most populous of the 50 states. According to the United States Census Bureau, the state's estimated population as of 2024 is 7.22 million.