According to later tradition, Agustín de Iturbide and insurgent leader Vicente Guerrero symbolically reconciled at Acatempan/Teloloapan, enabling cooperation that would soon crystallize in the Plan of Iguala. Some modern historians note the episode’s documentation is debated, but it remains a conventional marker for the alliance that helped end the war.
Iturbide issued the Plan of Iguala, proposing an independent Mexican constitutional monarchy and the “three guarantees” (religion, independence, and union). The plan provided a political framework that drew together former royalists and insurgents behind a shared settlement.
The Plan of Iguala’s coalition took military form as the Army of the Three Guarantees (Ejército Trigarante), combining Iturbide’s former royalist forces with insurgent elements. This army became the key instrument for securing recognition and control across New Spain.
The Battle of Azcapotzalco was fought as Trigarante forces tightened pressure around Mexico City. It is commonly described as among the last significant military actions of the independence war’s final phase, clearing the way for entry into the capital weeks later.
Iturbide and Juan O’Donojú signed the Treaty (Convention) of Córdoba, largely adopting the Plan of Iguala’s terms and accepting Mexican independence in principle. Spain’s government later rejected the treaty, but it was pivotal in the immediate transfer of authority.
The Army of the Three Guarantees made a triumphal entry into Mexico City, marking the effective consummation of independence in the capital and setting the stage for a new national government under the empire project associated with Iturbide.
Mexico’s independence was formally proclaimed in the Declaration of Independence of the Mexican Empire, drafted and signed in Mexico City under the Provisional Governmental Board. The act framed separation from Spain and asserted national sovereignty.
A Sovereign Provisional Governing Junta (Junta Provisional Gubernativa) began administering independent Mexico, providing a stopgap legislative authority while elections and arrangements were made for a constituent congress and the imperial executive (regency).
The elected Constituent Congress assembled to draft a constitution for the new state, taking over from the Provisional Junta. Its creation intensified debates over sovereignty, representation, and the extent of imperial executive power.
After political mobilization in his favor, Congress declared Iturbide emperor, transforming the post-independence settlement into a personal monarchy. His accession marked the formal start of the First Mexican Empire under Agustín I.
Agustín I’s coronation ceremony took place in the Mexico City Metropolitan Cathedral, publicly sacralizing and legitimizing the new imperial regime. The event underscored the empire’s monarchical and Catholic political symbolism.
Amid escalating conflict with legislators, Iturbide dissolved Congress, deepening opposition to imperial rule and fueling the perception that the empire was turning authoritarian. The move helped catalyze provincial and military resistance that followed.
Santa Anna and allied leaders issued the Plan of Casa Mata, calling for a new constituent congress and rejecting the political order created under Iturbide’s dissolved legislature. The plan quickly gained adherence in the provinces, isolating the emperor.
Facing widespread defection and political collapse, Iturbide abdicated, effectively ending the First Mexican Empire. His fall opened the way for a republican transition and a reconfiguration of executive authority.
Congress established a triumvirate known as the Supreme Executive Power to govern during the transition away from monarchy. This step formalized the institutional shift toward republican governance after Iturbide’s abdication.
Congress annulled Iturbide’s designation as emperor, treating the coronation as invalid rather than accepting abdication as a legitimate transfer. This action aimed to reset constitutional legitimacy and remove the imperial precedent from the new political order.
First Mexican Empire under Agustín de Iturbide (1821–1823)
