Deserted by his gunners, and abandoned by the escort which had been ordered to support him, the young subaltern still held his ground.  With the sole assistance of a sergeant, of stauncher mettle than the rest, he was loading and firing his solitary field-piece, rejoicing, as became the son of a warrior race, in the hot breath of battle, and still more in the isolation of his perilous position.  To stand alone, in the forefront of the fight, defying the terrors from which others shrank, was the situation which of all others he most coveted; and under the walls of Chapultepec, answering shot for shot, and plying sponge and handspike with desperate energy, the fierce instincts of the soldier were fully gratified.  Nor was Magruder the man to proffer prudent counsels.  A second gun was hoisted across the ditch; the men rallied; the Mexican artillery was gradually overpowered, and the breastwork stormed.  The crisis of the struggle was already past.  Pillow’s troops had driven the enemy from their intrenchments at the base of the hill, and beneath the shadows of the majestic cypresses, which still bear the name of the Grove of Montezuma, and up the rugged slopes which tower above them, pressed the assaulting columns.  A redoubt which stood midway up the height was carried.  The Mexicans fell back from shelter to shelter; but amid smoke and flame the scaling ladders were borne across the castle ditch, and reared against the lofty walls were soon covered with streams of men.  The leaders, hurled from the battlements on to the crowd below, failed to make good their footing, but there were others to take their places.  The supports came thronging up; the enemy, assailed in front and flank, drew back disheartened, and after a short struggle the American colours, displayed upon the keep, announced to the citizens of Mexico that Chapultepec had been captured.  Yet the victory was not complete.  The greater part of the garrison had fled from their intrenchments before the castle had been stormed; and infantry, cavalry, and artillery, in wild confusion, were crowding in panic on the causeways.  But their numbers were formidable, and the city, should the army be rallied, was capable of a protracted defence.  Not a moment was to be lost if the battle was to be decisive of the war.  The disorder on Chapultepec was hardly less than that which existed in the ranks of the defeated Mexicans.  Many of the stormers had dispersed in search of plunder, and regiments and brigades had become hopelessly intermingled in the assault of the rocky hill.  Still the pursuit was prompt.  Towards the San Cosme Gate several of the younger officers, a lieutenant by name Ulysses Grant amongst the foremost, followed the enemy with such men as they could collect, and Jackson’s guns were soon abreast of the fighting line.  His teams had been destroyed by the fire of the Mexican batteries.  Those of his waggons, posted further to the rear, had partially escaped.  To disengage the dead animals from the limbers and to replace them