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tin, 15 or 17 miles—the road, as the letters will show, being deemed impracticable by the Mexicans—arriving there on the 17th of August, being then 12 miles from the capital, and in front of the fortifications of San Antonio, which are about two and a half or three miles from San Augustin. These fortifications were threatened by a division, while the General, on the 19th, ordered a force to open a road in order to turn them to the left. This force had to pass what, in the letters, is called Pedregal, i. e., a surface of volcanic scoria, broken into every possible form, presenting sharp stones and deep fissures, exceedingly difficult for the passage of infantry, and impossible for that of cavalry, except by a single road, in front of which, and perfectly commanding it. General Valencia had established an entrenched camp on elevated ground, which camp he occupied with his division of 5000 men from San Luis Potosi, every where in the letters spoken of as the "flower" of the Mexican army. He had twenty-three pieces of superb artillery, and was covered by a large body of cavalry.—There was firing from and upon this entrenched camp during the afternoon of the 19th of August, but no serious demonstration was made upon it that day, the time being employed by the engineers in looking at the position and studying the grounds around it; so that the Mexicans both in the camp and in the city imagined they had gained a victory, merely because our army had not yet defeated them. The bells in the city were rung for joy, and Gen. Valencia distributed honors among the leading officers of his camp as the shades of evening left him in security with his lines.
During the night of the 19th, a body of our troops passed along a ravine under cover of a night made doubly dark by a heavy rain, and in the morning they had gained the rear of the entrenched camp, into which they plunged headlong before the astonished Mexicans had time to put themselves in position for defence. The assault was commenced and completed in the short period of seventeen minutes, though our troops were engaged during an hour or two in picking up the scattered fragments of the proud "division of the North"—Valencia himself disappearing altogether. Several names are applied to this entrenched camp, (San Geronimo, Padiernas, Magdalena, &c.,) but it is generally called Contreras, and it is about five or six miles from San Augustin, to the left of the San Antonio road. Passing by Contreras our troops, before mid-day, were in full march by San Angel and Coyoacan, towards Churubusco, where the Mexicans were in force in a church or convent strongly fortified. About five or six hundred yards beyond this convent the road by San Angel, &c.,
