The historical event that led to the declaration of independence from Spain in Mexican history was the Mexican War of Independence, which began in 1810 and culminated in 1821. The movement was sparked by social and economic inequality, inspired by Enlightenment ideas and earlier independence movements in other countries. Key figures such as Miguel Hidalgo and José María Morelos played significant roles in rallying the populace against Spanish rule. The movement was marked by numerous battles, sacrifices, and social upheaval, eventually resulting in the establishment of Mexico as an independent nation on September 27, 1821.