ned to obey the order. At 2.30
P.M. of August 20th Smith's troops moved to reach Valencia's
rear. Riley's brigade and Cadwallader's followed this movement.
General Shields with the New York regiment of Colonel Ward B. Burnett
and the South Carolina regiment under Colonel Pierce M. Butler
remained at the village, to intercept and cut off the enemy's retreat
and to prevent re-enforcements from reaching the Mexicans.

The night was intensely dark, and the streets of the village were very
narrow, cut into gullies and very muddy. A heavy rain was pouring
down, and the march was made under difficulties and necessarily slow.
General Smith's position was on an eminence about one thousand yards
from the enemy's works, from which point he made the attack. Riley
moved up the ravine to a slope leading to a high point of the ridge
and attacked the enemy some eight hundred yards distant. Cadwallader
followed Riley, and the Mounted Rifles and Engineer Company moved to a
position in rear of the force confronting Riley. The Third Infantry
and First Artillery were held in reserve. The attack was made as
ordered by General Smith, and the enemy fled, pursued by Riley, the
Mounted Rifles, and Engineers.

The Third Infantry and First Artillery, held in reserve, were attacked
by a force of cavalry, which was driven off, and Valencia was
completely routed. General Shields, who held the village, seized the
main road and cut off retreat in that direction. The enemy fled in the
greatest confusion. The battle of Contreras was one of the most
brilliant victories of the war. It opened the road to the City of
Mexico. Seven hundred of the enemy were killed, eight hundred and
thirteen prisoners were captured, including eighty-eight officers, of
whom four were generals; many standards, twenty-two pieces of brass
cannon, a large number of stands of small arms, seven hundred pack
mules, many horses, and large quantities of ordnance stores were added
to the outfit of the American army.

General Scott had planned to open up the way for the march of his army
to the City of Mexico by the way of Padierna. Knowing or believing
that a stubborn defense would be made by the Mexicans, he had ordered
General Worth to march from San Antonio on the morning of August 20th,
with Garland's brigade, by way of San Augustin to Padierna, to be
followed by General Quitman, who was ordered to leave a cavalry force
to hold San Antonio. But General Persifor F. Smith had won t