Fort Donelson, on the Cumberland River in northwestern Tennessee, was the site of a major battle in the Union campaign to control the Mississippi River Valley and split the Confederacy. On February 16, 1862, Confederate General Simon Buckner asked General Ulysses S. Grant for terms of surrender. Grant replied, "No terms except an unconditional and immediate surrender can be accepted." Buckner accepted the "ungenerous and unchivalrous terms which you propose" and surrendered what remained of the original 15,000-man-force.