Fort Donelson National Battlefield is a historic site located in Tennessee, commemorating a significant battle during the American Civil War. The battlefield was the site of the Union's first major victory in the Western Theater, which took place in February 1862. It played a crucial role in securing control of the Tennessee River and opened the way for further Union advances into the South. Visitors to the battlefield can explore various trails, monuments, and the Fort Donelson earthworks. The site also features a visitor center that provides educational exhibits and information about the battle and its impact on the war.