The work of both was now the construction of entrenchments, which consisted of earthworks sloping to either side, with logs as a parapet, and between these works and the opposing army were constructed what are known as abatis, felled trees, with the branches cut off, the sharp ends projecting toward the approaching forces. Lee's entrenchments were of such character as to increase the efficiency of his force. They were formed in the shape of a huge V with the apex flattened, forming a salient angle against the center of the Federal line. The Confederate lines were facing north, northwest, and northeast, the corps commanded by Anderson on the left, Ewell in the center, and Early on the right, the latter temporarily replacing A. P. Hill, who was ill. The Federals confronting them were Burnside on the left, Sedgwick and Warren in the center, and Hancock on the right. The day of the 9th was spent in placing the lines of troops, with no fighting except skirmishing and some sharp-shooting. While placing some field-pieces, General Sedgwick was hit by a sharpshooter's bullet and instantly killed. He was a man of high character, a most competent commander, of fearless courage, loved and lamented by the army. General Horatio G. Wright succeeded to the command of the Sixth Corps. Early on the morning of the 10th, the Confederates discovered that Hancock had crossed the Po River in front of his position of the day before and was threatening their rear. Grant had suspected that Lee was about to move north toward Fredericksburg, and Hancock had been ordered to make a reconnaissance with a view to attacking and turning the Confederate left. But difficulties stood in the way of Hancock's performance, and before he had accomplished much, Meade directed him to send two of his divisions to assist Warren in making an attack on the Southern lines. The Second Corps started to recross the Po. Before all were over Early made a vigorous assault on the rear division, which did not escape without heavy loss. In this engagement the corps lost the first gun in its most honorable career, a misfortune deeply lamented by every man in the corps, since up to this moment it had long been the only one in the entire army which could make the proud claim of never having lost a gun or a color.