Capture of forts Donelson, Tennessee. By U.S. Grant, January 1862.

UNITED STATES - CIRCA 1862: Area surrounding Fort Donelson, Tenn. including the Cumberland River, the town of Dover, and Fort Henry Road, and includes the locations of confederate earthworks as well as roads, buildings, woods, and creeks; he Battle of Fort Donelson was a very important victory for the North. The fall of this heavily fortified fort on the Tennessee River was deep in the heart of the confederacy. It ensured that Kentucky would stay with the Union. It was also here that U.S. Grant earned his nickname �Unconditional Surrender� and his promotion to Major General. When Confederate commander Buckner asked for surrender terms and Grant responded that, �No terms except unconditional and immediate surrender can be accepted.�, Hand Drawn Map (Photo by Buyenlarge/Getty Images)