With his engineer's eye, and from the heights overlooking the main field, he took in the whole situation. From various points he saw the awful battles of July 2d and 3d, which he described in two letters, written each time after merciful night came down upon the field of slaughter. He saw the charges and defeats, the counter-charges and the continued carnage, and the final cavalry onset made by the rebels. He was often under fire. An impression that lasted all his life, and to which he often referred, was the result of that great movement of Pickett's division across the field, after the long bombardment of the Federal forces by the Confederate artillery. Retiring before the heavy cannonade, Carleton had remained in the rear, until, hearing the cheers of the Union soldiers, he reached the slope in time to see the gray and brown masses in the distance. As the great wave of human life receded, that for a moment had pierced the centre of the Union forces, only to be hurled back and broken, Carleton rode out down the hill and on the plain into the wheat field. Then and there, seeing the awful debris, came the conviction that the rebellion had seen its highest tide, and that henceforth it would be only ebb. When is a battle over, and how can one know it? That night, Friday, and the next day, Saturday, Carleton felt satisfied that Lee was in full retreat, though General Meade did not seem to think so. Carleton's face was now set Bostonwards. Not being able to use the army telegraph, he gave his first thought to reaching the railroad. The nearest point was at Westminster, twenty-eight miles distant, from which a freight-train was to leave at 4 P. M. Rain was falling heavily, but with Whitelaw Reid as companion, Carleton rode the twenty-eight miles in two hours and a half. Covered with mud from head to foot, and soused to the skin, the two riders reached Westminster at 3.55 P. M. As the train did not immediately start, Carleton arranged for the care of his beast, and laying his blanket on the engine's boiler, dried it. He then made his bed on the floor of the bumping car, getting some sleep of an uncertain quality before the train rolled into Baltimore. At the hotel on Sunday morning he was seized by his friend, E. B. Washburn, Grant's indefatigable supporter and afterwards Minister to France, who asked for news. Carleton told him of victory and the retreat of Lee. "You lie," was the impulsive answer. Washburn's nerves had for days been under a strain. Then, after telling more, Carleton telegraphed a half-column of news to the _Journal_ in Boston. This message, sent thence to Washington, was the first news which President Lincoln and the Cabinet had of Gettysburg. After a bath and hoped-for rest, Carleton was not allowed to keep silence. All day, and until the train was entered at night for New York, he was kept busy in telling the good news.