Cinco de Mayo is still celebrated in Mexico, but is considered a minor holiday. It was largely unknown in the U.S. until the 1960s, until Latino activists started raising its profile.
The holiday celebrates the Mexican victory over France at the Battle of Puebla, May 5, 1862. Mexican Independence Day is celebrated September 16.
Mexico had been invaded by Spain, France and Great Britain in late 1861, but within six months Spain and Britain had pulled out. With the \Civil War in the U.S. raging north of the Mexican border, the French decided to take advantage of the chaos and invade Mexico, which had been torn apart by war in the late 1850s.
The French made inroads in April 1862, but in May, at the town of Puebla — about 85 miles east of Mexico City — a small Mexican army under the command of Ignacio Zaragoza defeated a larger French contingent. Zaragoza was born in what’s now Goliad, Texas, about 60 miles due north of Corpus Christi.
It was a classic David-over-Goliath victory, and it’s been celebrated ever since for its symbolic value, even though the French did eventually take over Mexico and establish the short-lived Second Mexican Empire under the Emperor Maximilian.