Cinco de Mayo
Cinco de Mayo is a national holiday in Mexico and is celebrated on May 5th every year. It commemorates the Battle at Puebla on this day in 1862 when Mexican army defeated the French (and a Mexican "traitor" army).
Mexico declared its independence many years prior, in 1810, but it took a full 11 years for the Spanish occupiers to leave. During this time of struggle Mexico accured big foreign debts. After years of missed payments, England and France, the biggest creditors, eventually sent troops to Mexico to force collection. But when the English realized that France's intention was its own territory's expantion, they left.
The Mexicans then engaged in another struggle with the French, which were eventually defeated at Puebla
Cinco de Mayo is celebrated throughout the country but also, due to the large Mexican minority, in many parts of America.