The document summarizes three important dates in Mexican history celebrated as holidays: 1) September 13th honors Los Niños Heroes, six military cadets who died defending Castillo de Chapultepec from American forces invading Mexico City in 1847. 2) September 16th commemorates Mexican Independence Day in 1810 when Miguel Hidalgo issued the Grito de Dolores calling for independence from Spanish rule. 3) September 20th marks the start of the Mexican Revolution in 1910 against Porfirio Díaz's long authoritarian rule which ultimately removed him from power, though the revolution's leader Francisco Madero was later assassinated.