Having turned the forest on the west, and arriving opposite to the north centre of Chapultepec, Worth came up with the troops in the road, under Colonel Trousdale, and aided, by a flank movement of a part of Garland's brigade, in taking the one gun breastwork, then under the fire of Lieutenant Jackson's section of Captain Magruder's field battery. Continuing to advance, this division passed Chapultepec, attacking the right of the enemy's line, resting on that road, about the moment of the general retreat consequent upon the capture of the formidable castle and its outworks.
Arriving some minutes later, and mounting to the top of the castle, the whole field to the east lay plainly under my view.
There are two routes from Chapultepec to the capital, the one on the right entering the same gate, Belen, with the road from the south, via Piedad; and the other obliquing to the left, to intersect the great western or San Cosmo road, in a suburb outside of the gate of San Cosmo.
Each of these routes (an elevated causeway) presents a double roadway on the sides of an aqueduct of strong masonry and great height, resting on open arches and massive pillars, which together afford fine points both for attack and defence. The sideways of both aqueducts are, moreover, defended by many strong breastworks at the gates, and before reaching them. As we had expected, we found the four tracks unusually dry and solid for the season.
Worth and Quitman were prompt in pursuing the retreating enemy, the former by the San Cosmo aqueduct, and the latter along that of Belen. Each had now advanced some hundred yards.
Deeming it all important to profit by our successes, and the consequent dismay of the enemy, which could not be otherwise than general, I hastened to dispatch from Chapultepec, first Clarke's brigade, and then Cadwallader's, to the support of Worth, and gave orders that the necessary heavy guns should follow. Pierce's brigade was, at the same time, sent to Quitman, and, in the course of the afternoon, I caused some additional siege pieces to be added to his train. Then, after designating the 15th Infantry, under Lieutenant-Colonel Howard (Morgan, the Colonel, had been disabled by a wound at Churubusco), as the garrison of Chapultepec, and giving directions for the care of the prisoners of war, the captured ordnance and ordnance stores, I proceeded to join the advance of Worth, within the suburb, and beyond the turn at the junction of the aqueduct with the great highway from the west to the gate of San Cosmo.
At this junction of roads, we first passed one of these formidable systems of city defences, spoken of above, and it had not a gun! a strong proof, 1. That the enemy had expected us to fail in the attack upon Chapultepec, even if we meant anything more than a feint; 2. That, in either case, we designed, in his belief, to return and double our forces against the southern gates: a delusion kept up by the active demonstration of Twiggs and the forces posted on that side; and, 3. That advancing rapidly from the reduction of Chapultepec, the enemy had not time to shift guns—our previous captures had left him, comparatively, but few—from the southern gates.
Within those disgarnished works, I found our troops engaged in a street fight against the enemy posted in gardens, at windows, and on house-tops, all flat, with parapets. Worth ordered forward the mountain howitzers of Cadwallader's brigade, preceded by skirmishers and pioneers with pickaxes and crowbars, to force windows and doors, or to burrow through walls. The assailants were soon in an equality of position fatal to the enemy. By eight o'clock in the evening, Worth had carried two batteries in this suburb. According to my instructions, he here posted guards and sentinels, and placed his troops under shelter for the night. There was but one more obstacle, the San Cosmo gate, (custom-house,) between him and the great square in front of the cathedral and palace, the heart of the city; and that barrier it was known could not, by daylight, resist our siege guns thirty minutes.
I had gone back to the foot of Chapultepec, the point from which the two aqueducts begin to diverge, some hours earlier, in order to be near that new depot, and in easy communication with Quitman and Twiggs, as well as with Worth.
From this point I ordered all detachments and stragglers to their respective corps, then in advance; sent to Quitman additional siege guns, ammunition, intrenching tools; directed Twiggs' remaining brigade, Riley's from Piedad, to support Worth, and Captain Steptoe's field battery, also at Piedad, to rejoin Quitman's division.