The document summarizes important dates in Mexican history: September 13 honors the Niños Heroes, six young cadets who died defending Mexico City's Chapultepec castle from U.S. invasion; September 16 celebrates Mexico's independence from Spain, sparked by Miguel Hidalgo ringing church bells and calling citizens to arms in 1810; November 20 marks the Mexican Revolution from 1910-1920 when citizens revolted against Porfirio Diaz's 30-year autocratic rule seeking change and an end to exploitation.