The Confederate surrender at Vicksburg on the 4th July 1863 was a disaster for the South during the American Civil War, because it caused the loss of control of the Mississippi River Valley. President Jefferson Davis was ultimately responsible, not because the Union had superior resources, but because of his own shortcomings, chief of which were: not providing a co-ordinated defence plan for the West, incorrectly assessing the capabilities of his western generals, failing to understand the deficiencies in his own capabilities, and not reacting to the change needed, as the North developed new tactics to prosecute the war. In early 1863, the Confederate geographical command structure was split along the line of the Mississippi River, but the Union attacked using both banks. General Joseph E. Johnston had Vicksburg within his in command, but he was based in Chattanooga. His subordinate, Lieutenant-General John C. Pemberton was left in isolation at Vicksburg, but he did enjoy the direct support of Davis. They agreed on the wrong defensive strategy, contrary to Johnston's wishes, which left him in an impossible position. This work has studied the interaction between these Southern leaders, as they lost the supposedly impregnable city of Vicksburg.