Colonel Duncan had observed a threatening movement on the left. Santa Anna had ordered Álvarez to move down on the American flank with his whole force. With a cloud of cavalry in advance, Álvarez came on and was met by the fire of Duncan's battery, which opened upon the Mexicans within easy range. The cavalry halted, and after a few discharges of the American guns had ploughed their ranks they were thrown into confusion and retreated. Major Sumner came up with his dragoons to accelerate the Mexican retirement; before the dragoons had completed their formation for a charge the Mexicans were in full retreat towards the Haçienda Morales. A twenty-four-pounder which had been sent up by Worth continued a smart fire upon the Mexicans until they were out of range. The dragoons held their position on the left till the end of the action. As soon as the Mexicans were out of range Duncan's guns were turned upon Casa Mata and the enemy's troops around it. Under their fire the place was soon abandoned, General Perez commencing his retreat by the right as the fall of Molino del Rey had cut off his direct communication with Chapultepec. His line of retreat kept him under the fire of Duncan's guns, which inflicted a severe loss upon his troops. With the fall of the Casa Mata the battle of Molino del Rey was ended and the Americans were in full possession of the field.
But while they were exulting over their victory a Mexican column, under General Barragan, advanced with the evident intention of retaking the Molino; it was met by a heavy fire from the American guns, together with some that had been captured from the Mexicans, and very soon the Mexican column gave way and fled in disorder. A little later another Mexican force advanced in the direction of Casa Mata, but this, like the other column, was checked by the American artillery and a heavy volley from the infantry. As the Mexicans retreated, the Americans followed them several hundred yards along the road.
