General Scott, to whom it was communicated through the indefatigable diligence of Captain Lee, of the Engineers.
At 3 o'clock A. M. of the 20th August, the movement commenced on the rear of the enemy's camp, led by Colonel Riley and followed successively by Cadwallader's and Smith's brigades, the whole force being commanded by General Smith.
The march was rendered tedious by rain, mud and darkness; but, about sun rise, Riley reached an elevation behind the Mexicans, whence he threw his men upon the works, and, storming the entrenchments, planted his flag upon them in seventeen minutes.
Meanwhile Cadwallader brought on the general assault by crossing the deep ravine in front and pouring into the work and upon the fugitives, frequent volleys of destructive musketry. Smith's own brigade under the temporary command of Major Dimick, discovered, opposite and outside the work, a long line of Mexican cavalry drawn up in support, and by a charge against the flank, routed the horse completely, while General Shields held masses of cavalry, supported by artillery, in check below him, and captured multitudes who fled from above.