Under these circumstances General Scott directed the holding of the front of the enemy without making an attack until further orders.
On the 18th of August, the day of reaching San Augustin Tlalpam, Garland's brigade secured a position within easy range of the advanced intrenchments of San Antonio, but where his troops were protected by an artificial embankment that had been thrown up for some other purpose than defense.

General Scott at once set his engineers reconnoitring the works about Contreras, and on the 19th movements were commenced to get troops into positions from which an assault could be made upon the force occupying that place.

The Pedregal on the north and north-east, and the mountain on the south, made the passage by either flank of the enemy's defences difficult, for their work stood exactly between those natural bulwarks; but a road was completed during the day and night of the 19th, and troops were got to the north and west of the enemy.
This affair, like that of Cerro Gordo, was an engagement in which the officers of the engineer corps won special distinction.

In fact, in both cases, tasks which seemed difficult at first sight were made easier for the troops that had to execute them than they would have been on an ordinary field.

The very strength of each of these positions was, by the skill of the engineers, converted into a defence for the assaulting parties while securing their positions for final attack.