After a three-day siege on the Cumberland River, Confederate commander Simon Bolivar Buckner asked for surrender terms. Grant famously replied that only 'unconditional and immediate surrender' would be accepted, earning him the nickname 'Unconditional Surrender' Grant. The victory, with nearly 12,000 Confederates captured, was the Union's first major triumph of the Civil War and opened Tennessee to Northern advance.
The siege had been brutal even by the standards of a war still finding its shape. Confederate troops, many without proper winter coats, endured freezing rain and sleet in open trenches while Union gunboats and infantry pressed the fort from the river and land. On February 15, Confederate forces had nearly broken out, only to inexplicably retreat back into the fort after winning ground, a decision that doomed the garrison.
When Buckner, an old friend of Grant's from West Point, sent a note asking for terms, Grant's reply was blunt: 'No terms except an unconditional and immediate surrender can be accepted.' It was a stunning departure from the genteel surrender negotiations common earlier in the war. Buckner, with no options left, called the terms 'ungenerous and unchivalrous' but accepted anyway.
The fall of Fort Donelson, following the capture of Fort Henry ten days earlier, tore open the Confederate defensive line across Kentucky and Tennessee. Nashville fell within weeks. Grant, previously a struggling former army officer working in his father's leather shop before the war, became a national hero overnight and the initials 'U.S.' in his name were rebranded in headlines across the North.
Key people: Ulysses S. Grant, Simon Bolivar Buckner