Cinco de Mayo is typically assumed by Anglos (and many Hispanics) to be a Mexican version of July 4. That's not really accurate. Moreover, although it ostensibly celebrates a temporal military victory by the Mexican Army over a French expeditionary force in the city of Puebla on May 5, 1862, the date first took hold among Mexicans living north of the border. Cinco de Mayo was really a way of commemorating the Civil War -- ours, not Mexico's. News traveled slowly in the mid-19th century, so Mexican miners in California's gold fields didn't hear of the Puebla defenders' victory over French troops dispatched by Napoleon III until three weeks later.
Fireworks were set off in the Gold Rush country of Northern California; rifles were fired into the air at Nevada mining camps; spontaneous fiestas broke out among work crews as far north as Oregon. The most organized celebrations among the Mexican diaspora in the West were in Los Angeles, where Mexican American politicians hosted rallies and delivered patriotic speeches.
At the time, many people in the United States believed that the French intention was to arm the Confederacy of Robert E. Lee and Jefferson Davis. This was an overblown worry, but Cinco de Mayo was a chance for Mexican Americans living in California to revel in their loyalty to the Union.
"Cinco de Mayo is not a Mexican holiday," UCLA professor David E. Hayes-Bautista told me a number of years ago. "It is an American Civil War holiday, created spontaneously by Mexicans and Latinos living in California who supported the fragile cause of defending freedom and democracy during the first years of that bloody War Between the States."
To Mexican Americans in the 1860s, most of whom loathed slavery, the Battle of Puebla became their version of the Battle of Shiloh: a victory for the Union. Mexico native Jose Alamillo, a professor of Chicano studies at California State University, Channel Islands, first heard of Cinco de Mayo in elementary school -- after moving to the U.S. with his family when he was 8 years old.
"It's not a Mexican holiday, not an American holiday, but an American-Mexican holiday," Alamillo told Time magazine. "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."
Over the years, it has evolved into a broader, and equally noble cause: celebrating the ethnic pluralism that makes this free country a vibrant cultural cauldron. And it's hardly "cultural appropriation" for non-Hispanics to observe it -- it's the very essence of the day.
Carl M. Cannon is the Washington bureau chief for RealClearPolitics. Reach him on Twitter @CarlCannon.