On January 29, 1863, General Grant took command of the army intended to operate against Vicksburg, the last place held by the rebels on the Mississippi, and the only point at which they could cross the river and keep up communication with their armies and territory in the southwest. It was the first high ground below Memphis, was very strongly fortified, and was held by a large army under General Pemberton. The complete possession of the Mississippi was absolutely essential to the National Government, because the control of that great river would cut the Confederacy in two, and do more, probably, than anything else, to make the overthrow of the Rebellion both speedy and certain.