When Lee came to the banks of the little river the next morning he found his opponent had crossed over and destroyed the bridges. The Army of the Potomac was once more united. During the day the Federal wagon trains were safely passed over White Oak Swamp and then moved on toward the James River. Lee did not at first divine McClellan's intention. He still believed that the Federal general would retreat down the Peninsula, and hesitated therefore to cross the Chickahominy and give up the command of the lower bridges. But now on the 29th the signs of the movement to the James were unmistakable. Early on that morning Longstreet and A. P. Hill were ordered to recross the Chickahominy by the New Bridge and Huger and Magruder were sent in hot pursuit of the Federal forces. It was the brave Sumner who covered the march of the retreating army, and as he stood in the open field near Savage's Station he looked out over the plain and saw with satisfaction the last of the ambulances and wagons making their way toward the new haven on the James. In the morning of that same day he had already held at bay the forces of Magruder at Allen's Farm. On his way from Fair Oaks, which he left at daylight, he had halted his men at what is known as the "Peach Orchard," and from nine o'clock till eleven had resisted a spirited fire of musketry and artillery. And now as the grim warrior, on this Sunday afternoon in June, turned his eyes toward the Chickahominy he saw a great cloud of dust rising on the horizon. It was raised by the troops of General Magruder who was pressing close behind the Army of the Potomac. The Southern field-guns were placed in position. A contrivance, consisting of a heavy gun mounted on a railroad car and called the "Land Merrimac," was pushed into position and opened fire upon the Union forces. The battle began with a fine play of artillery. For an hour not a musket was fired. The army of blue remained motionless. Then the mass of gray moved across the field and from the Union guns the long tongues of flame darted into the ranks before them. The charge was met with vigor and soon the battle raged over the entire field. Both sides stood their ground till darkness again closed the contest, and nearly eight hundred brave men had fallen in this Sabbath evening's battle. Before midnight Sumner had withdrawn his men and was following after the wagon trains. The Confederates were pursuing McClellan's army in two columns, Jackson closely following Sumner, while Longstreet was trying to cut off the Union forces by a flank movement. On the last day of June, at high noon, Jackson reached the White Oak Swamp. But the bridge was gone. He attempted to ford the passage, but the Union troops were there to prevent it. While Jackson was trying to force his way across the stream, there came to him the sound of a desperate battle being fought not more than two miles away, but he was powerless to give aid.