Hancock was in command of the Second; Warren, the Fifth; and Sedgwick, the Sixth. Sheridan was at the head of the cavalry. The Ninth Corps acted as a separate army under Burnside, and was now protecting the Orange and Alexandria Railroad. As soon as Meade had crossed the Rapidan, Burnside was ordered to move promptly, and he reached the battlefield of the Wilderness on the morning of May 6th. On May 24th his corps was assigned to the Army of the Potomac. The Union forces, including the Ninth Corps, numbered about one hundred and eighteen thousand men. The Army of Northern Virginia consisted of three corps of infantry, the First under Longstreet, the Second under Ewell, and the Third under A. P. Hill, and a cavalry corps commanded by Stuart. A notable fact in the organization of the Confederate army was the few changes made in commanders. The total forces under Lee were about sixty-two thousand. After assuming command, Grant established his headquarters at Culpeper Court House, whence he visited Washington once a week to consult with President Lincoln and the Secretary of War. He was given full authority, however, as to men and movements, and worked out a plan of campaign which resulted in a series of battles in Virginia unparalleled in history. The first of these was precipitated in a dense forest, a wilderness, from which the battle takes its name. Grant decided on a general advance of the Army of the Potomac upon Lee, and early on the morning of May 4th the movement began by crossing the Rapidan at several fords below Lee's entrenched position, and moving by his right flank. The crossing was effected successfully, the line of march taking part of the Federal troops over a scene of defeat in the previous spring. One year before, the magnificent Army of the Potomac, just from a long winter's rest in the encampment at Falmouth on the north bank of the Rappahannock, had met the legions of the South in deadly combat on the battlefield of Chancellorsville. And now Grant was leading the same army, whose ranks had been freshened by new recruits from the North, through the same field of war. By eight o'clock on the morning of the 4th the various rumors as to the Federal army's crossing the Rapidan received by Lee were fully confirmed, and at once he prepared to set his own army in motion for the Wilderness, and to throw himself across the path of his foe. Two days before he had gathered his corps and division commanders around him at the signal station on Clark's Mountain, a considerable eminence south of the Rapidan, near Robertson's Ford. Here he expressed the opinion that Grant would cross at the lower fords, as he did, but nevertheless Longstreet was kept at Gordonsville in case the Federals should move by the Confederate left.