[October 25th, Grant was placed in command of the Department of the
Tennessee and headquarters were established at Oxford, Miss.
Reinforcements continued to come from the North, and by November 2d,
he was prepared to take the initiative. This, he said, was a great
relief after two and a half months of continued defence over a large
district where every citizen was an enemy. On November 3d, Grant left
Jackson for the campaign against Vicksburg, which did not end until
July 4, 1863.
Vicksburg was very important to the enemy on account of its position.
It was the only link connecting the parts of the Confederacy separated
by the Mississippi. While held by the enemy, free navigation of the
river was impossible. During the winter of '62 to '63 there were
exceptionally heavy rains and continuous high water on the
Mississippi.