By the end of July, conditions indicated to Farragut that a withdrawal from Vicksburg was necessary. In the hot, fetid atmosphere of the river the disease rate had so increased that only 800 of Williams’ 3,000 men were fit for duty. At the same time, the steadily falling waters threatened to maroon his deep-draught vessels. Farragut, with Williams’ troops aboard, moved down river to New Orleans, while Davis steamed up river, leaving Vicksburg unopposed. The initial expedition against Vicksburg had failed. [Illustration: THE STRATEGIC SITUATION JULY 1862] [Illustration: _Scene of Sherman’s assault against the Bluffs at Chickasaw Bayou._ From _Battles and Leaders of the Civil War_.] With the Union withdrawal, communications between the sections of the Confederacy east and west of the Mississippi, which had been temporarily curtailed, were resumed. From Vicksburg to Port Hudson, a distance of 250 miles by river, the Mississippi was now in Confederate hands. Into the Mississippi, just above Port Hudson, emptied the Red River which drained much of the trans-Mississippi South, and down which great stores of food were being floated to supply the armies of the Confederacy. It was imperative for the North to close off this important supply route. GRANT’S FIRST FAILURE AT VICKSBURG. In October 1862, Grant, who had won the sobriquet of “Unconditional Surrender” at Fort Donelson and had rallied his army from near defeat at bloody Shiloh, was placed in command of the Department of the Tennessee with headquarters at Memphis; his objective—to clear the Mississippi River. The same month, Lt. Gen. John C. Pemberton, a West Pointer, born and raised in Pennsylvania, who had served with Grant in the Mexican War, was placed in command of the Confederate troops defending the Mississippi; his objective—to keep the Southern supply line open and prevent loss of the river. Vicksburg would be the focus of military operations for both commanders. The first full-scale expedition against Vicksburg was initiated in December 1862, with Grant pushing southward through the State of Mississippi to strike Vicksburg from the rear as Maj. Gen. William Tecumseh Sherman, with an army of 32,000 men aboard 60 transports, proceeded down river from Memphis. Grant anticipated that his advance would pull Pemberton’s army away from Vicksburg, permitting Sherman to make a lodgment on the bluffs immediately north of the city against a greatly reduced garrison. On December 20, Maj. Gen. Earl Van Dorn, with a striking force of 3,500 Confederate cavalry, swung in behind the Union line of march, capturing and burning $1,500,000 of military goods at Grant’s supply base in Holly Springs. Unwilling to wage a campaign without a base of supply, Grant abandoned his campaign and returned to Memphis.