On May 1st, 1846, Mexican 
General Arista crossed the 
Rio Grande into Texas with 
6,000 troops.  By May 3rd he 
had reached Camp Texas and 
begun to seige the defenders.  
On May 4th, Major Brown noticed
he was surrounded, and by 
previous arrangement with 
General Zachary Taylor, fired 
his eighteen pounders to let 
him know that help was needed.

Taylor, currently at his base 
at Point Isabel, quickly left 
with 2,200 troops.  It would 
be four days before he would 
arrive though as the wagon 
train of 200 plus wagons would 
slow him considerably.

On May 8th Taylor reached 
Arista's lines at Palo Alto.  
Outnumbered two to one, Taylor 
decided that he would have to 
rely on his artillery.  The 
one area where he had 
superiority in numbers, 
his artillery would need to 
carry the battle instead of 
the infantry if he was going 
to win.  At 2:30 p.m. Mexican 
artillery opened up at a range 
of about a half mile.  Taylor 
immediately deployed his 
artillery and began to return 
fire.

During the next five hours 
Arista would try many times to 
close with Taylor but each 
attempt was beaten back by the 
superior artillery fire of 
Taylor's artillerymen.  
Eventually the Mexican 
soldiers broke under the 
barrage of cannon balls and 
fled.   