The Battle of Fort Donelson took place from February 11 to February 16, 1862, during the American Civil War. It was a significant conflict between the Union forces, led by Ulysses S. Grant, and the Confederate defenders. The Union aimed to capture the fort to gain control of the Cumberland River, which was vital for transportation and supply routes. After several days of fighting, the Confederates, under Simon Bolivar Buckner, ultimately surrendered on February 16. This victory for the Union marked a turning point in the war, opening up the Confederate heartland to further Union advances and boosting Northern morale.