Sunday marks the 162nd anniversary of the Battle of Puebla, which is what inspired the Cinco de Mayo holiday.
Although the holiday celebrates a key victory the Mexican military had over French forces, the events were arguably important for the U.S. as well.
What led to the Battle of Puebla?
According to the Library of Congress, Mexican President Benito Juarez had cut payments of foreign debts to the United Kingdom, Spain and France in 1861 as Mexico was struggling financially. The three nations sent ships to Veracruz in hopes of collecting debt.
Mexico worked out agreements with the U.K. and Spain, allowing their forces to return home. France, however, wanted more than just unpaid debt. It wanted the entire country.
A battle ensued.
What happened on Cinco de Mayo
Remember, Mexico was broke at the time. So when the French military advanced on Puebla, Mexican forces were expected to struggle.
According to the LOC, Texas-born general Ignacio Zaragoza led a "rag-tag" army to a decisive victory over the French, forcing French forces to retreat. The French army had to call in reinforcements, which took many months to arrive.
The victory was important in the U.S.
In 1862, the Union was in the midst of a fierce battle with the Confederacy. At that point, the Confederate government was not recognized by any other government, but France was considering becoming allies with the South.
While it’s unknown what would have happened had France initially won the Battle of Puebla, its defeat meant that a potential alliance with the South was on hold.
By the time French reinforcements were able to take control of Mexico in 1863, the Union was well on its way to victory.
The Library of Congress featured an 1870 article out of San Francisco noting a celebration of the battle.
"The subsequent Cinco de Mayo celebrations in California and elsewhere in the Southwest were fitting because California Latinos were strong Union supporters and had helped finance Juarez’s army," the Library of Congress said.
Library of Congress research guide Dani Thurber said as she reads documents about the day, she is reminded of the impact of the battle.
“Unfortunately, until I got to college, I didn't really understand the significance of that particular battle," she said. "I knew it wasn't Mexico's Independence Day because I grew up, I'm Latina so I know Mexico's Independence Day is September 16th. It's a huge party, as well."
"I just think maybe it's because of the time of the year," Thurber added. "It's about to be summer and it's a nice, it is a wonderful party, and it's a wonderful thing to celebrate even if you're not as familiar with the historical aspects."
How Cinco de Mayo is celebrated today
The U.S. has over 37 million residents of Mexican descent, making up nearly 60% of the entire U.S. Hispanic population, according to the U.S. Census Bureau.
Although the day is not an official holiday in Mexico, its spring date and relevance in the U.S. has made it a popular day to celebrate Mexican-American culture.
"Since the 19th century, Mexican Americans in the United States have used Cinco de Mayo to celebrate Mexican culture in their adopted country. In recent decades, Cinco de Mayo has grown beyond the Mexican American community and is celebrated by Americans of all ethnicities," the U.S. Embassy said.
President Joe Biden and first lady Jill Biden will host a Cinco de Mayo reception at the White House on Monday.
Learning more on Cinco de Mayo
The Library of Congress recently obtained 36 Mexican letters from a rare books dealer. The Library of Congress said the letters serve as a reminder of how important the Battle of Puebla played in the second French intervention and the U.S. Civil War.
The letters are among a number of documents from primary sources the Library of Congress has for examination.
Although the letters have not been digitized yet, Thurber noted that many of its resources are online at LOC.Gov.
“I mean, the Library of Congress has wonderful resources, primary sources, books, newspapers, journals, every kind of resource you can imagine,” Thurber said. “And we are, it's a library of Congress, we still serve Congress, but we also serve the American people and users all over, across the world.”