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During this battle, on September 13, the 4th Division, under John A. Quitman, spearheaded the attack against Chapultepec and carried the castle. Future Confederate generals George E. Pickett and James Longstreet participated in the attack. Serving in the Mexican defense were the cadets later immortalized as Los Niños Héroes (the "Boy Heroes"). The Mexican forces fell back from Chapultepec and retreated within the city. Attacks on the Belén and San Cosme Gates came afterwards. The treaty of Guadalupe Hidalgo was signed in what is now the far north of the city.

When did the castle fall?
on September 13