According to History.com, the Mexicans were both vastly outnumbered and poorly supplied as they prepared for the French.
But in the end, nearly 500 French soldiers died and less than 100 Mexicans were killed. While the victory wasn’t a major win in the overall war (the French won the next year and occupied the region for five years), it represented “a great symbolic victory.”
The battle stems from Mexico's immense debt to France in the early 1860s, which led to Napoleon III's decision to send troops to not only overtake Mexico City, but also to help form a Confederate-friendly country that would neighbor the South, according to Time.
Independence Day in Mexico, when it gained its independence from the Spanish colonial government in 1810, is commemorated on Sept. 16.
Cinco de Mayo isn’t all that popular in Mexico.
The holiday is primarily celebrated in Puebla, where the 1862 battle took place. There, locals gather for a big, colorful parade and reenact the war dressed as French and Mexican soldiers before breaking out in song and dance after the reenacted victory.
But for many Mexicans, it’s just another day.
How did the holiday get so popular in the U.S.?
The holiday's popularity began as the unlikely Battle of Puebla Mexican victory reached California-based Latinos, many of whom were not only happy about Mexico's victory, but had been rooting for Union forces in the Civil War at the same time, Time reported.
As California Latinos found out, they formed a network of patriotic organizations to raise money for the Mexican troops.
"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," Jose Alamillo, a California professor of Chicano studies, told Time.
Former President Franklin D. Roosevelt’s enactment of the Good Neighbor Policy in 1933 is also considered part of the holiday’s popularization.
But the party-filled Cinco de Mayo Americans celebrate today didn’t become popular until U.S. beer companies began targeting the Spanish-speaking population in the 1970s and 80s, Alamillo said.
Today, Cinco de Mayo in the U.S. is primarily a celebration of Mexican-American culture.
How many Mexican-Americans are there in the U.S.?
According to the U.S. Census, the Hispanic population of the U.S. as of July 1, 2015 was 56.6 million -- 17.6 percent of the country's total population.
And of the Hispanic population in 2015, 63.4 percent were of Mexican origin.
Americans consume a crazy amount of avocados on Cinco de Mayo.
According to Forbes, Americans eat 81 million pounds of avocados on Cinco de Mayo.
This is great news for Mexico’s economy, considering 82 percent of America’s avocados come from Mexico.
In 2017, avocado prices were at an all-time high due to high demand and reduced harvests in other major avocado production markets.