Barely taking time to breathe his troops, Smith followed in pursuit toward the city. By ten o'clock in the morning he reached San Angel, which Santa Anna evacuated as he approached. The General-in-Chief and the generals of division had by this time relieved Smith of his command. Scott rode to the front, and in a few brief words told the men there was more work to be done that day. A loud cheer from the ranks was the reply. The whole force then advanced to Coyacan, within a mile of Churubusco, and prepared to assault the place.
Santa Anna considered it the key to the city, and awaited the attack in perfect confidence with thirty thousand men. The defences were simple. On the west, in the direction of Coyacan, stood the large stone convent of San Pablo, which, as well as the wall and breastworks in front, was filled with infantry, and which contained seven heavy guns. A breastwork connected San Pablo with the _tête de pont_ over the Churubusco River, four hundred yards distant. This was the easternmost point of defence, and formed part of the San Antonio causeway leading to the city. It was a work constructed with the greatest skill--bastions, curtain, and wet ditch, everything was complete and perfect--four guns were mounted in embrasure and barbette, and as many men as the place would hold were stationed there. The reserves occupied the causeway behind Churubusco. Independently of his defences, Santa Anna's numbers--nearly five to one--should have insured the repulse of the assailants.
By eleven--hardly seven hours having elapsed since the Contreras camp had been stormed, five miles away--Twiggs and Pillow were in motion toward the San Antonio causeway. Nothing had been heard of Worth, who had been directed to move along the east side of the Pedregal on San Antonio, but it was taken for granted he had carried the point, and Scott wished to cut off the retreat of the garrison. Twiggs was advancing cautiously toward the convent when a heavy firing was heard in advance. Supposing that a reconnoitring party had been attacked, he hastily sent forward the First Artillery, under Dimmick, through a field of tall corn, to support them. No sooner had they separated from the main body than a terrific discharge of grape, canister, and musketry assailed them from the convent. In the teeth of the storm they advanced to within one hundred yards of that building, and a light battery under Taylor was brought up on their right, and opened on the convent.