An unconditional surrender is a surrender in which no guarantees, reassurances, or promises are given to the surrendering party. It is often demanded with the threat of complete destruction, extermination or annihilation.

The Siege of Vicksburg was the final major military action in the Vicksburg campaign of the American Civil War. In a series of maneuvers, Union Major General Ulysses S. Grant and his Army of the Tennessee crossed the Mississippi River and drove the Confederate Army of Mississippi, led by Lieutenant General John C. Pemberton, into the defensive lines surrounding the fortress city of Vicksburg, Mississippi, leading to the successful siege and Confederate surrender.