Sherman made his assault on December 29 at Chickasaw Bayou, 5 miles north of Vicksburg. The land here was a low, swampy shelf lying between the Yazoo River and the bluffs. The few dry causeways over which the Federal infantry could advance were completely covered by Confederate rifle and artillery fire from the bluffs 200 feet above. The Union Army lost nearly 2,000 men against Confederate casualties of less than 200. Tersely, Sherman reported his defeat: “I reached Vicksburg at the time appointed, landed, assaulted and failed.” [Illustration: GRANT’S FIRST MOVE AGAINST VICKSBURG _DECEMBER 1862_] Grant’s advance was halted and turned back when Van Dorn’s cavalry raid destroyed the huge Union supply base at Holly Springs. Sherman assaulted the bluffs at Chickasaw Bayou, 5 miles north of Vicksburg and was repulsed. [Illustration: _The Confederate ironclad ram _Arkansas_ engaging the combined Union fleets at Vicksburg._ From _Battles and Leaders of the Civil War_.] _The Bayou Expeditions: Grant Moves Against Vicksburg—and Fails_ By the end of January, Grant had arrived at the Union encampment at Milliken’s Bend, 30 miles north of Vicksburg, and assumed leadership of the operations against Vicksburg. His army, numbering about 45,000, was divided into three corps under General Sherman, Maj. Gen. John McClernand, and Maj. Gen. James Birdseye McPherson. Cooperating with the army, and providing aid without which the bayou expeditions would not have been possible, was the Western Flotilla under Porter. This fleet consisted of 11 ironclads, 38 wooden gunboats, rams, and sundry auxiliary craft mounting over 300 guns and carrying a complement of 5,500. The war in the West now hinged upon the effectiveness of this combined land and naval force. Under Grant’s direction it maneuvered over hundreds of miles of river and bayou seeking to outflank Vicksburg. The capture of the city would result not from great battles but from a war of movement. THE GEOGRAPHICAL PROBLEM OF VICKSBURG. The capture of Vicksburg proved difficult partly because of the topography of the area, which so favored defense of the city as to render the fortress almost impregnable to attack. To move against the city it was necessary to reach the bluffs which extended north and south and on which Vicksburg had been built. Behind the bluffs, to the east, lay dry ground on which an army might maneuver; below the bluffs, on both sides of the river, flooded swamplands prevented ground movements. With his army behind the bluffs, either above or below, Grant might come to grips with Pemberton’s Army of Vicksburg. Unless he reached the bluffs, capture of the city would be impossible; it could not be assaulted from the river.