The document summarizes key dates in Mexican history. On September 13th, it describes six young Mexican military cadets known as "Niños Heroes" who died defending Chapultepec Castle from American soldiers during the Mexican-American War in 1847. On September 16th, it discusses how Miguel Hidalgo initiated Mexico's war for independence from Spain in 1810 with his famous call to arms. Finally, on November 20th, it provides a brief overview of the Mexican Revolution that began in 1910 against President Porfirio Diaz and transformed the country through a new constitution in 1917.