(May 5, 1862), battle fought at Puebla, Mexico, between the army of the liberal government headed by Benito Juárez and the French forces sent by Napoleon III to establish a French satellite state in Mexico. The battle, which ended in a Mexican victory, is celebrated in the national calendar of Mexican holidays as Cinco de Mayo (5th of May).

The route taken by the French toward the capital was blocked by the fortified city of Puebla. Incautiously the French general Charles Latrille Laurencez ordered a frontal assault up the steep Cerro de Guadalupe against the Mexican position, which was fortified by a ditch and a brick wall. The Mexicans under General Ignacio Zaragoza repulsed the attackers, who lost about 1,000 men and then retreated to the coast. Credit for the Mexican victory is shared by a young officer (and future president), Brigadier General Porfirio Díaz, who succeeded in turning back a flank of the invading French army.

The following March, the French general Élie-Frédéric Forey, with reinforcements from France, laid siege to Puebla. Its approximately 30,000 defenders, commanded by Gonzáles Ortega, after having used up all ammunition and food, surrendered; most were sent to France as prisoners. On April 2, 1867, Díaz (Díaz, Porfirio) retook the city, ending the French occupation. The Cinco de Mayo holiday symbolizes Mexico's determination to thwart foreign aggression.