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. All the troops
with General Scott in the valley of Mexico, except a part of the
division of General Quitman at San Augustin Tlalpam and the brigade of
Garland (Worth's division) at San Antonio, were engaged at the battle of
Contreras, or were on their way, in obedience to the orders of their
chief, to reinforce those who were engaged. The assault was made on the
morning of the 20th, and in less than half an hour from the sound of the
advance the position was in our hands, with many prisoners and large
quantities of ordnance and other stores. The brigade commanded by
General Riley was from its position the most conspicuous in the final
assault, but all did well, volunteers and regulars.

From the point occupied by Garland's brigade we could see the progress
made at Contreras and the movement of troops toward the flank and rear
of the enemy opposing us. The Mexicans all the way back to the city
could see the same thing, and their conduct showed plainly that they did
not enjoy the sight. We moved out at once, and found them gone from our
immediate front. Clarke's brigade of Worth's division now moved west
over the point of the Pedregal, and after having passed to the north
sufficiently to clear San Antonio, turned east and got on the causeway
leading to Churubusco and the City of Mexico. When he approached
Churubusco