Mexico's Independence in 1821: From Grito to Sovereignty

On September 27, 1821, the Army of the Three Guarantees entered Mexico City, consummating independence. The formal declaration occurred September 28, 1821 (not September 16 — that's the 1810 Grito). Here's the full arc.

1810: The Spark — Grito de Dolores

• Sept 16, 1810: Father Miguel Hidalgo y Costilla rings church bell in Dolores, Guanajuato, calling for revolt against Spanish rule.
• Indigenous/mestizo army forms; captures Guanajuato, Valladolid, nears Mexico City.
• 1811: Hidalgo captured, executed. Leadership passes to José María Morelos.
• 1815: Morelos executed. Insurgency fragments into guerrilla bands (Guerrero, Victoria).

1820–21: The Turn — Iturbide & the Plan de Iguala

• 1820: Liberal revolution in Spain (Riego) restores 1812 Constitution. Mexican conservatives (clergy, military, elites) fear loss of privileges.
• Augustin de Iturbide (royalist officer) switches sides, allies with Vicente Guerrero (insurgent leader).
• Feb 24, 1821: **Plan de Iguala** proclaimed: Three Guarantees — Independence, Religion (Catholic exclusivity), Union (all castes equal).
• Army of Three Guarantees forms; sweeps south.

Aug–Sep 1821: The Endgame

• Aug 24: **Treaty of Córdoba** — Spanish Viceroy Juan de O'Donojú (newly arrived) recognizes Mexican independence under Plan de Iguala terms. Not ratified by Spain.
• Sept 27: Iturbide's army enters Mexico City unopposed.
• Sept 28: **Declaration of Independence of the Mexican Empire** signed by 36 notables (Iturbide, O'Donojú, bishops, generals).
• Sept 28 – 1822: Provisional governing junta; Iturbide proclaimed Emperor Agustín I (May 1822).

Spain's Formal Recognition

• 1822: Spanish Cortes rejects Treaty of Córdoba.
• 1836: Spain finally recognizes Mexican independence (Santa María–Calatrava Treaty).

Significance

• First successful independence in Spanish America (after Haiti 1804).
• Conservative-led (vs. liberal revolutions south) — preserved Church, hierarchy, military.
• Set template: pronunciamiento + plan + caudillo — repeated across 19th-century Mexico.
• Territory: Included present-day US Southwest (lost 1848), Central America (briefly united 1821–23).

Mexico's independence was a negotiated transfer (Iturbide–O'Donojú), not a revolutionary overthrow — unique in Latin America. The 1810 Grito ignited the struggle; the 1821 Plan de Iguala finished it.