I wrote a song myself about the san patricios here are the lyrics
there is a sample of it too on cdbaby.com the album its on is "songs from an outpost". I wrote the song to the air of the scottish song dainty davey

47 too long a year, men died in chains men died in fear
some were lost under Irish sky and some on Mexico's fields were hung.
The gallows there 14 feet high two score men condemned to die
hung at noon in scorching heat, three hours they waited bound hand and feet.

47 too dark a year, men shook their chains and fell in fear
from Vera Cruz a flag unfurled many men rallied round it.
A Mexican eagle and a Celtic cross under the green flag men were lost
shot down as soldiers, hung as slaves their cruel fate a shallow grave.

Birds wouldn't cross the Pedragal through it General Lee he carved a path
Valencia's army were routed there Churubusco's fate was calling.
The Yankees tumbled through high corn at Churubusco we shot them down
Mexican guns they soon gave out with bayonets we joined the slaughter.

Three times the white flag swung round three times O'Riley pulled it down
when blood ran down into the sound only then did they surrender.
The Mexican eagle and a Celtic cross under the green flag men were lost
Shot down as soldiers, hung as slaves their cruel fate a shallow grave.

The gallows there 14 feet high two score men condemned to die
Hung at noon in scorching heat, three hours they waited bound hand and feet.