a primary obstacle; and fortified positions at San Antonio, San Angel, and Churubusco, with an intrenched camp at Contreras, were likewise to be surmounted before the southern causeways could be reached.  Beyond these there yet remained the formidable castle of Chapultepec and the strong enclosure of Molino del Rey, to be stormed before the city gates could be reached.  Powerful batteries had been mounted at all these points, and ample garrisons detailed to serve them.  The bone and muscle of Mexico were there.

Goaded by defeat, Santa Anna never showed so much vigor; ambition fired Valencia; patriotism stirred the soul of Alvarez; Canalizo, maddened by the odium into which he had fallen, was boiling to regain his soubriquet of the “Lion of Mexico.”  With a constancy equal to anything recorded of the Roman Senate, the Mexican Congress, on learning of the defeat at Cerro Gordo, had voted unanimously that anyone opening negotiations with the enemy should be deemed a traitor; and the citizens with one accord had ratified the vote.  Within six months Mexico had lost two splendid armies in two pitched battles against the troops now advancing against the capital; but she never lost heart, and her spirit quailed not.

The engineers reporting that the fortress on El Penon could not be carried without a loss of one-third the army, Scott decided to move by the south of the lakes; and Worth accordingly advanced, leading the van, as far as San Augustin, nine miles from the city of Mexico.  There a large field of lava, known as the Pedregal, barred the way.  On the one side, two miles from San Augustin, the fortified works at San Antonio commanded the passage between the field and the lake; on the other, the ground was so much broken that infantry alone could advance, and General Valencia occupied an intrenched camp, with a heavy battery, near the village of Contreras, three miles distant.  Scott determined to attack on both sides, and sent forward General William J. Worth on the east, and General Gideon J. Pillow and General David E. Twiggs on the west.  The latter advanced as fast as possible over the masses of lava on the morning of the 19th, and by 2 P.M. a couple of light batteries were placed in position and opened fire on the Mexican camp.

At the same time General Persifor Smith conceived the plan of turning Valencia’s left, and hastened along the path through the Pedregal in the direction of a village called San Jeronimo.  Colonel Riley followed.  Pillow sent Cadwallader’s brigade on the same line, and later in the day Morgan’s regiment was likewise despatched toward that point.  They drove in the Mexican pickets and skirmishers, dispersed a few parties of lancers, and occupied the village without loss.  Seeing the movement, Santa Anna hastened to Valencia’s support with twelve thousand men.  He was discovered by Cadwallader just as the latter gained the village road; and appreciating the vast importance of preventing a junction between