<P> A common misconception in the United States is that Cinco de Mayo is Mexico's Independence Day, the most important national patriotic holiday in Mexico . Mexico celebrates Independence Day on the 16th of September, commemorating the beginning of the war of Independence (September 16, 1810, Grito de Dolores). Mexico also observes the culmination of the war of Independence, which lasted 11 years, on the 27th of September . </P> <P> Since the 1930s, a re-enactment of the Battle of Puebla has been held each year at Peñón de los Baños, a rocky outcrop close to Mexico City International Airport . </P>

What caused the conflict that lead to the battle of puebla