extent, covered with the Pedregal or the field of broken lava which we have already mentioned. This mass of jagged volcanic matter, we must remember, was at that time barely passable with difficulty for infantry, and altogether impassable for cavalry or artillery, save by a single mule path. North, beyond the fortified hacienda and headquarters of Santa Anna at San Antonio, the country opened. A line of field works, the lake of Xochimilco, a few cultivated farms, and vast flooded meadows, were on its right to the east, but from the hacienda, a road branches off to the west, leading around the northern edge of the Pedregal or lava field through Coyoacan and San Angel, whence it deflects southwardly to Contreras. The main road, however, continues onward, northwardly, from the hacienda of San Antonio, until it crosses the Churubusco river at the strong fortification we have described. Beyond Churubusco the highway leads straight to the gate of San Antonio Abad, whence a work had been thrown north-westwardly towards the citadel. The city of Mexico, built on the bed of an ancient lake, was on a perfect level, nor were there any commanding or protecting elevations of importance around it within two or three miles, and the first of these, beyond this limit, were chiefly on the north and west.
Thus, General Santa Anna, in front, on the main road to the city, at the massive fortified hacienda of San Antonio, blocked up the highway in that direction, protected on his right by the barrier of the Pedregal; and by the lake of Xochimilco, the field works, and the flooded country on his left. General Valencia had been placed by him with his troops at San Angel, on the western edge of the valley, and at the village of Coyoacan, a little further east in the lap of the valley, on roads communicating easily with his position at San Antonio, while they commanded the approaches to the city by the circuitous path of the Pedregal around the edge of the valley from San Agustin de las Cuevas, through Contreras or Padierna. Valencia and Santa Anna were consequently within supporting distance