tion of
Magruder's battery, to drive in the Mexican pickets. Lieutenant George
B. McClellan placed the artillery in position, but before it was ready
for action it received a fire from the guns on the elevated ridge
beyond Padierna. The remainder of Smith's brigade and the other
section of Lieutenant John Bankhead Magruder's battery were ordered
forward, and the Mexicans were driven back. General Bennet Riley's
brigade was ordered to the right, and to pass over the _pedregal_ and
take possession in the enemy's rear. General Cadwallader's brigade was
ordered to support Riley's movement. General Scott, perceiving that
re-enforcements were approaching Valencia from the City of Mexico,
ordered a regiment of General Franklin Pierce's brigade to move
forward and occupy San Geronimo, and General James Shields with two
regiments (New York, and Palmetto, South Carolina) was ordered forward
as a support. General Persifor F. Smith now moved to the front across
the _pedregal_, having left detachments as supports to the artillery
of Magruder and Callender, which were ordered to open fire on the
beginning of General Smith's movement. This movement of General
Persifor F. Smith was led and conducted by Lieutenant Gustavus W.
Smith. When this force reached the village or town of San Geronimo a
large force of the enemy came in sight. Pierce's brigade was at once
ordered to the front, and was met by a heavy fire. General Pierce
having been disabled, Colonel Robert Ransom, of the Ninth Infantry,
was in command of the forces, which were conducted by Lieutenant Isaac
Ingles Stevens, and moved to the right and front of Magruder's
battery. Ransom, uniting with the detachment left by General Smith,
took possession of Padierna, driving the Mexican General Mendoza.
Riley's command was the first to pass the _pedregal_, when it occupied
the road on the opposite side with Captain Simon Henry Drum's company
of the Fourth Artillery. A detachment of Mexican lancers escorting a
train was encountered and captured.

Riley's command continued its advance, when a company of Mexican
lancers was met and repulsed by Captain Silas Casey's company. A
mounted force, under the Mexican General Frontera, consisting of two
regiments, was met and repulsed by the Second Infantry under Captain
Charles T. Morris and the Seventh Infantry under Lieutenant-Colonel
Joseph Plympton. General Frontera was killed while leading a charge.
Riley now withdrew to San Geronimo, which