In 1862, the French Army, which invaded under the pretext of collecting on Mexico’s defaulted external debt (but actually to fulfill Napoleon III’s dreams of empire) was defeated by a much smaller Mexican army led by 33 year old General Ignacio Zaragoza at the Battle of Puebla. The large, professional, and well equipped French force arrogantly attacked strong Mexican fortifications, anchored by the twin forts of Fort Loreto and Fort Guadalupe on the approaches to the town of Puebla. The French were repulsed multiple times, despite a significant advantage in artillery and a two to one advantage in troops. During their retreat, Mexican cavalry pursued and inflicted debilitating casualties. The survivors retreated back to Vera Cruz, where they held against the victorious Mexican pursuers.
The defeat prompted Napoleon III to send massive reinforcements, who eventually took Puebla and Mexico City. However, the Mexican victory at Puebla provided a morale boost to the Mexican people and united, at least temporarily, the various factions that had fought each other so bitterly just the year before in the Reform War. The Mexicans would fiercely continue their fight against Napoleon III’s puppet, the Hapsburg Emperor Maximilian’s Second Mexican Empire, until 1867 when the United States began enforcing the Monroe Doctrine after the end of the US Civil War. With America’s support, the Mexicans drove the French and the Imperialists out of Mexico and established the Mexican Republic.
The Mexican victory at Puebla, which happened on 5th of May, is today celebrated as Cinco De Mayo in the Mexican State of Puebla and more generally in the United States as a celebration of Mexican heritage.