ade would go on when Riley faced to the left; and, as
soon as he passed Riley, Cadwallader would also face to the left and
come into action on Riley's right. Smith's own brigade would turn to the
left before reaching the extremity of the second ridge. The Third
Infantry and First Artillery would advance in the deep valley between
the two ridges; whilst the Rifle Regiment, with the engineer company
leading, would ascend the steep slope of the second ridge, and get into
position on the flank, or rear, of the Mexican detachment which Riley
was to attack in front. In the meantime the head of Smith's brigade had
come within view, near the foot of the steep slope of the second ridge,
and was moving towards the Mexican main line.

General Smith pointed out to me the route to be taken to reach the top
of the second ridge; and ordered that the engineer company and rifles
should bear to the right, and on getting near the Mexican detachment,
remain concealed, and quiet, until Riley's brigade became well engaged;
then join in the attack and pursuit of that detachment.

With these specific instructions, I was ordered to rejoin my company;
and Lieutenant Beauregard was directed to take general charge of the
movements of Smith's brigade. When Beauregard and I reached the top of
the second ridge we found we were 50 yards, or less, in rear of the
Mexican detachment, which was facing Riley. All was quiet. In a very
few moments Riley's fire commenced.

The engineer company, followed by the rifle regiment was then forming in
line, under cover, in rear of the Mexican detachment, whose attention
was concentrated on Riley, in their front. We were between that
detachment and the Mexican works. A small portion only of the Rifle
Regiment was in line, when the firing with Riley became very severe, and
the order was given for the engineer company and rifles to rise and fire
into the backs of the enemy. That fire was very destructive. The
Mexicans were astounded; faced squarely about, and in a moment
precipitately retreated.

In my official report it is stated that: "Colonel Riley's advance became
engaged with a very strong picket, some 300 yards or more from the rear
of the [enemy's] battery, near the crest of the ridge; the engineers and
rifles came up at once in position to take the picket in rear, delivered
a deadly volley within 50 yards, cheered and rushed on. The enemy's
force fled; the head of our column crossed the line of their retreat