Mexico became independent in 1821 after the Mexican War of Independence.
The conflict began on 16 September 1810, when the priest Miguel Hidalgo y Costilla issued the Grito de Dolores, calling for an uprising against Spanish colonial rule. The rebellion developed into a long and complicated war involving insurgents, royalists, shifting alliances, and competing political goals.
Agustín de Iturbide, formerly a royalist officer, joined Vicente Guerrero and agreed to the Plan of Iguala in 1821. Their alliance promoted Mexican independence, Roman Catholicism, and a constitutional monarchy. The Army of the Three Guarantees entered Mexico City on 27 September 1821, effectively ending Spanish rule.
Mexico’s independence is celebrated on 16 September, commemorating Hidalgo’s 1810 call rather than the final military victory. The country’s formal separation from Spain was later recognized through the Treaty of Córdoba, although Spain did not immediately accept the agreement.