The San Blas Battalion was a Mexican infantry unit founded in 1823 in San Blas, Nayarit. Under the name "Batallón Activo Guardacostas de San Blas" (San Blas Active Coastguard Battalion), it saw action on several occasions culminating in the Mexican–American War. The battalion participated in the Battle of Chapultepec, where commanded by Lt. Colonel Felipe Santiago Xicoténcatl, aided in the defense of the Military Academy in the Chapultepec Castle. Of the 300 men comprising the battalion, only a few survived the battle.