The prairie of Palo Alto was naturally suited for the first battle of the Mexican War. The low-lying, coastal prairie was surrounded by tree covered rises that inspired its Spanish name, "Tall Timber." The Matamoros to Point Isabel Road crossed the vast field on the western end. It was this very road Zachary Taylor's force of 2,300 men and 400 wagons were following.
In the early hours of May 8, 1846, General Mariano Arista led his 3,200 men onto this field. The Mexican general positioned his cannons on the roadway to block the U.S. advance. He also placed lines of infantry and additional artillery across the prairie. Arista capped his mile-long battle line with his cavalry. Using this formation, Arista hoped to outflank and crush the approaching U.S. Army.
General Taylor arrived at Palo Alto around midday on May 8. As U.S. troops marched out of the cover of mesquite thickets at the northern edge of the field, they paused to entrench their supply train. When this was done, they advanced to within 700 yards of the Mexican lines. The stage was set.
The Battle Begins
When the Mexican cannon began firing, U.S. troops assumed battle formation, but did not advance to engage Mexican forces. General Taylor feared a charge would leave his supply train vulnerable to attack. The general decided to hold his infantry and cavalry in a defensive formation and rolled his artillery forward to respond.
Taylor’s use of 18-pound siege cannons was significant. The guns were originally intended for duty at Fort Texas. The devastating fire of these huge guns tore at the Mexican lines, causing numerous casualties. By contrast, Mexican artillery was much less effective and frequently fired short of the U.S. lines.
Arista attempted to answer the devastating effects of Taylor’s artillery by sending cavalry troops against the right flank of the U.S. line. General Anastasio Torrejón's lancers swept across the western edge of the field, but soon became bogged down by the uneven ground and dense growth.
By the time the charge reached its destination, the U.S. 5th Infantry had positioned itself to repel the attack. Torrejón's horsemen regrouped and attempted an attack on the U.S. supply train. Torrejón's charge was turned back again. This time Taylor's light artillery provided support against the charge.
Torrejón's withdrawal permitted U.S. forces to move forward along the road. Taylor’s continued concern for the supply train and a grass fire that erupted in the middle of the field prevented a full advance. As heavy smoke from the fire brought shooting to a halt, the U.S. advance resulted in little more than a rotation of the battle lines.