Because the French supported the Confederacy, the victory at Puebla was celebrated in California, a supposedly free state in which a significant portion of the Mexican population were considered "negro."
“By the time [Latinos in California] heard about the news of the battle, they began to raise money for the Mexican troops and they formed a really important network of patriotic organizations,” says Jose Alamillo, a professor of Chicano studies at California State University Channel Islands. “They had to kind of make the case for fighting for freedom and democracy and they were able to link the struggle of Mexico to the struggle of the Civil War, so there were simultaneous fights for democracy.”
But there was also a foreboding of evil to come in the story. The military hero in the Battle of Puebla was a young officer named Porfirio Diaz. Diaz leveraged this military fame into politics, to become the US-supported dictator of Mexico for several decades.
It was my own hero, Ricardo Flores Magon (born on the real Mexican Independence Day - September 16) who started the revolution from exile in Los Angeles, which eventually overthrew Diaz.
So to truly “celebrate” Cinco De Mayo, we should continue the struggle.
Y la lucha sigue . . .