Following the delay of the Union offensive against Richmond at the Siege of Yorktown, Johnston oversaw a tactical withdrawal to the outskirts of Richmond, where defenses had already been prepared. Longstreet's division formed the rearguard, which was heavily engaged at the Battle of Williamsburg on May 5. There, Union troops beginning with Joseph Hooker's division of the Union III Corps, which was commanded by Samuel P. Heintzelman, came out of a forest into open ground to attack Longstreet's men. To protect the army's supply wagons, Longstreet launched a strong counterattack with the brigades of Cadmus M. Wilcox, A. P. Hill, Pickett and two other regiments. The assault drove the Union soldiers back. Finding the ground he occupied untenable, Longstreet requested reinforcements from D.H. Hill's division a little further up the road and received Early's brigade, to which was later added the entire division. Early then launched a fruitless and bloody attack well after the wagons had already been safely evacuated. Overall, the battle was a success, protecting the passage of Confederate supply wagons and delaying the advance of McClellan's army toward Richmond. The affair resulted in the capture of nine Union artillery pieces. Longstreet reported 9,000 Confederate troops engaged compared to 12,000 Union troops, and the Confederates suffered fewer casualties. McClellan inaccurately characterized the battle as a Union victory in a dispatch to Washington.