Chapiltepec, a Mexican fortress, built upon a rock of the same name, 150 or 200 ft. high, about 2 m. S. W. of the city of Mexico. At the time of the war with the United States it was heavily armed, had a frontage of 900 ft., and defended a causeway which formed the approach to the city. At the base of the hill, in front, was the wall of an aqueduct; in the rear an old powder mill, known as Molino del Rev. The castle was the seat of the national military academy, and was defended by Gen. Bravo and a picked force. Santa Anna, with the greater portion of his army, occupied the city of Mexico, and was in communication with Chapultepec. On Sept. 12, 1847, Gen. Scott first stormed Molino del Rey, then, under cover of a demonstration against the city, brought four batteries to bear upon the castle from an opposite ridge, and after a heavy fire of a day and a half made the attack in two columns, simultaneously upon the E. and W. sides of the fortress. The American loss was slight, the Mexican much heavier. The day after the fall of the castle the city of Mexico was occupied by the American forces.