Mexican Army 4 Pound Copper Cannonball Fired During the Battle of Palo Alto on May 8, 1846

Palo Alto Battlefield and Resaca de la Palma Battlefield are two of a handful of American battlefields where solid copper cannonballs were used. Copper was a surplus material coming out of the Mexican silver mines during the 1800s. Mexico found many uses for the copper, including making munitions to equip their army. Archeological investigations at Palo Alto have revealed that the Mexican Army used copper for both cannonballs and canister shot, in addition to the more conventional iron cannonballs and shot.