Learning on the return of Captain Lee, that Shields in the rear of Churubusco was hard pressed, and in danger of being outflanked, if not overwhelmed, by greatly superior numbers, I immediately sent under Major Sumner, 2d Dragoons, the Rifles (Twiggs' reserve) and Captain Sibley's troop, 2d Dragoons, then at hand, to support our left, guided by the same engineer.
About an hour earlier, Worth had, by skillful and daring movements upon the front and right, turned and forced San Antonio: its garrison, no doubt, much shaken by our decisive victory at Contreras.
His second brigade (Colonel Clarke's) conducted by Captain Mason, Engineer, assisted by Lieutenant Hardcastle, Topographical Engineer, turned to the left, and by a wide sweep came out upon the high road to the capital. At this point the heavy garrison (three thousand men) in retreat was, by Clarke, cut in the centre: one portion, the rear, driven upon Dolores, off to the right, and the other upon Churubusco, in the direct line of our operations. The first brigade (Colonel Garland's), same division, consisting of the 2d Artillery, under Major Gait, the 3d Artillery, under Lieutenant-Colonel Belton, and the 4th Infantry, commanded by Major F. Lee, with Lieutenant-Colonel Duncan's field battery (temporarily) followed in pursuit through the town, taking one general prisoner, the abandoned guns (five pieces), much ammunition and other public property.
The forcing of San Antonio was the second brilliant event of the day. Worth's division being soon reunited in hot pursuit, he was joined by Major-General Pillow, who, marching from Coyoacan and discovering that San Antonio had been carried, immediately turned to the left according to my instructions, and, though much impeded by ditches and swamps, hastened to the attack of Churubusco.
The hamlet or scattered houses bearing this name, presented besides the fortified convent, a strong field-work (tête-de-pont) with regular bastions and curtains, at the head of a bridge over which the road passes from San Antonio to the capital.
The whole remaining forces of Mexico, some twenty-seven thousand men, cavalry, artillery and infantry, collected from every quarter, were now in, on the flanks, or within supporting distance of those works, and seemed resolved to make a last and desperate stand; for if beaten here, the feebler defences at the gates of the city, four miles off, could not, as was well known to both parties, delay the victors an hour. The capital of an ancient empire, now of a great republic, or an early peace, the assailants were resolved to win. Not an American, and we were less than a third of the enemy's numbers, had a doubt as to the result.
The fortified church or convent, hotly pressed by Twiggs, had already held out about an hour, when Worth and Pillow, the latter having with him Cadwallader's brigade, began to manœuvre closely upon the tête-de-pont, with the convent at half gunshot to their left. Garland's brigade (Worth's division), to which had been added the light battalion under Lieutenant-Colonel C. F. Smith, continued to advance in front and under the fire of a long line of infantry off on the left of the bridge; and Clarke, of the same division, directed his brigade along the road or close by its side. Two of Pillow's and Cadwallader's regiments, the 11th and 14th, supported and participated in this direct movement; the other (the Voltigeurs) was left in reserve. Most of these corps, particularly Clarke's brigade, advancing perpendicularly, were made to suffer much by the fire of the tête-de-pont, and they would have suffered greatly more by flank attacks from the convent, but for the pressure of Twiggs on the other side of that work.
This well-combined and daring movement at length reached the principal point of attack, and the formidable tête-de-pont was at once assaulted and carried by the bayonet. Its deep wet ditch was first gallantly crossed by the 8th and 5th Infantry, commanded respectively by Major Waite and Lieutenant-Colonel Martin Scott, followed closely by the 6th Infantry (same brigade), which had been so much exposed on the road, the 11th regiment, under Lieutenant-Colonel Graham, and the 14th, commanded by Colonel Trousdale, both of Cadwallader's brigade, Pillow's division. About the same time the enemy in front of Garland, after a hot conflict of an hour and a half, gave way in a retreat toward the capital.
The immediate result of this third signal triumph of the day were three field pieces, one hundred and ninety-two prisoners, much ammunition, and two colors taken at the tête-de-pont.
Lieutenant I. F. Irons, 1st Artillery, aid-de-camp to Brigadier-General Cadwallader, a young officer of great merit and conspicuous in battle on several previous occasions, received in front of the work a mortal wound. (Since dead.)