necessarily held to their position. In moving off, the former could gain one day the start. This brought the only difficult parts of the Chalco route actually nearer General Scott than the Mexican chief. If to this we add the delay necessary in moving heavy artillery and breaking up from a fortified position, it would seem that, instead of oversight, it was rather impossible for General Santa Anna to meet our forces sooner than he did."
The description of the various routes to the capital has necessarily acquainted the reader with the important Mexican defences on the north, the east, and the north-east of the capital, both by military works hastily thrown up after Santa Anna's retreat from Cerro Gordo, and by the encampment of large bodies of soldiery. We thus, already know a part of the external line of defences at El Peñon, Mexicalzingo, Tezcoco, Santiago Zacualco, and the Pass north of Tenepantla. But in addition to these, there are others that must be noticed on the south and west of the capital, which it should always be recollected is situated in the lap of the valley, but near the western edge of the gigantic rim of mountains.