Spain supported the colonies in the American Revolution. They were at war with Britain in Europe at the time and they provided money and supplies to the colonies as well as attacking several British positions along the Mississippi River and ramping up the European War. The Fourth of July holiday doesn’t even mark a battle, it marks the signing of the Declaration of Independence, the war had been being fought for over a year at that point.

You don’t try to assassinate people for altruistic reasons, and I have no ancestors that killed Spaniards on the 4th of July.