Major General Ulysses S. Grant and his army in Tennessee had been trying to capture the Confederate fort of Vicksburg in Mississippi though previous attempts had been blocked due to the bad travelling terrain in the entire Western theater. Grant had surprised John Pemberton and had defeated the Confederate forces making them move away from the Mississippi River to where the Union could get access to the fort. Union victories at Champion Hill and Black Bridge had weakened Pemberton's forces, leaving the fort retrievable and Pemberton no other choice than to surrender.