Fort Donelson (dŏn´əlsən), Confederate fortification in the Civil War, on the Cumberland River at Dover, Tenn., commanding the river approach to Nashville, Tenn. After capturing Fort Henry, on the Tennessee River (Feb. 6, 1862), General Ulysses S. Grant, on Feb. 12, marched his men 12 mi (19 km) to Fort Donelson, which he proceeded to invest. Although assisted by gunboats, his army was repulsed by the Confederates. The Confederates were thrown back by the Union forces on the next day, after attempting to retreat. The fort fell on Feb. 16, opening the way for the advance on Nashville. Fort Donelson National Battlefield and National Cemetery is there (see National Parks and Monuments, table).