Which play of Jose M Hernandez tells an artisan who forged cannons for the use Spaniards?

The play by José M. Hernandez that tells the story of an artisan who forged cannons for the use of Spaniards is "Martín Fierro".

While not the central theme, the play does feature a character named El Gaucho who forges cannons for the Spanish army. This act of defiance and betrayal against his fellow gauchos is a significant part of the narrative.