Mexican War of Independence

The day after the triumphal entry into the capital, the new governing authorities issued and signed the Declaration of Independence of the Mexican Empire at the National Palace. This act gave formal documentary expression to the political separation achieved on the battlefield and in negotiation. It announced to domestic and foreign audiences that Spanish sovereignty in Mexico had ended and that a new nation now existed. While later political systems would change, the declaration stands as the legal and symbolic culmination of the Mexican War of Independence, joining the memory of 1810’s rebellion with the institutional birth of the Mexican state in 1821.

On 27 September 1821, the Army of the Three Guarantees marched triumphantly into Mexico City, effectively consummating independence after more than a decade of war. This ceremonial entrance mattered as much politically as militarily: it showed that the coalition forged by the Plan of Iguala had secured the capital and displaced viceregal rule. The event closed the armed conflict that had begun with Hidalgo’s cry in 1810 and signaled the transfer from insurgency to state formation. It also established Agustín de Iturbide as the dominant figure in the immediate postwar settlement, even as debates over monarchy, representation, and sovereignty remained unresolved.

On 24 August 1821, Agustín de Iturbide and the newly arrived Spanish political chief Juan O'Donojú signed the Treaty of Córdoba in Veracruz. The agreement accepted the basic framework of the Plan of Iguala and acknowledged that Mexico would be independent. Although the Spanish government later refused to ratify the treaty, it was still a crucial milestone because it showed that the highest Spanish authority then present in New Spain saw independence as unavoidable. Córdoba helped turn military and political momentum decisively in favor of the independence coalition and smoothed the transfer of authority in the final weeks of the war.

The final breakthrough came when royalist officer Agustín de Iturbide and insurgent leader Vicente Guerrero aligned behind the Plan of Iguala. Proclaimed on 24 February 1821, the plan proposed independence, the protection of Catholicism, and unity between American- and Spanish-born elites. Its importance lay in forging a coalition broad enough to end the long war: insurgents gained the possibility of victory, while conservative sectors found an independence formula that safeguarded religion and social order. This political compromise transformed the conflict by converting many former defenders of Spanish rule into supporters of separation from Spain.

In 1817, Spanish liberal Francisco Javier Mina arrived on the Gulf Coast with volunteers, hoping to aid the Mexican insurgents against absolutist rule. Although foreign intervention on behalf of the rebellion remained limited, Mina’s expedition had outsized symbolic importance. It connected the Mexican struggle to broader Atlantic-era conflicts over constitutionalism, monarchy, and popular sovereignty. Militarily, the expedition was ultimately defeated, but politically it demonstrated that the cause of Mexican independence had international resonance and had survived the deaths of Hidalgo and Morelos. The war was no longer a local revolt; it had become part of a wider crisis of the Spanish imperial world.

After trial and degradation from the priesthood, José María Morelos was executed by firing squad in December 1815. His death deprived the insurgency of its most disciplined military commander and one of its clearest political minds. Yet, as with Hidalgo, execution did not extinguish the movement. Instead, leadership passed to regional figures such as Vicente Guerrero and Guadalupe Victoria, who kept resistance alive in difficult terrain. Morelos’s legacy endured in the constitutional and social ideas he had advanced, making his death both the end of a major insurgent phase and the preservation of a political program that later independent Mexico would continue to debate.

By late 1815, royalist counterinsurgency had weakened the territories held by the rebels. At Temalaca, Morelos was defeated and captured while attempting to protect members of the insurgent Congress. His capture was a severe blow because he had become the movement’s principal strategist, organizer, and political thinker after Hidalgo’s death. The event marked the collapse of the second major phase of the war, in which larger insurgent armies and congresses had tried to create national institutions. After Temalaca, the struggle survived mainly through scattered regional guerrilla resistance rather than through a unified central command.

Promulgated by the Congress of Anáhuac at Apatzingán, the Constitutional Decree for the Liberty of Mexican America was the insurgency’s most complete constitutional statement during the war. The document embraced representative government, divided powers, and republican principles, showing how far the movement had progressed from the more ambiguous royalism of 1810. Although wartime conditions prevented it from being fully implemented across the country, the constitution mattered as a political milestone. It signaled that the insurgents were not only fighting to expel Spanish authority but were also trying to define the legal structure and civic principles of a new Mexican state.

In November 1813, the insurgent Congress meeting at Chilpancingo issued the Solemn Act of the Declaration of Independence of Northern America. This represented the first formal declaration by insurgent authorities that New Spain was no longer dependent on the Spanish crown. The act was significant not because it immediately secured control over the whole territory, which it did not, but because it converted the rebellion into an explicit war for national sovereignty. By framing independence in legal and political terms, Congress strengthened the movement’s claim to legitimacy and laid groundwork for later constitutional and diplomatic developments.

When the Congress of Chilpancingo convened in September 1813, Morelos presented Sentimientos de la Nación, a foundational political program for the insurgent cause. The document moved the struggle beyond loyalty disputes within the Spanish monarchy and openly asserted that America was free and independent of Spain. It also advocated popular sovereignty, the division of powers, the abolition of slavery and caste distinctions, and a reduction of social privilege. This moment was crucial because it gave the independence movement a clearer ideological direction and linked military rebellion to a coherent project of nation-building and constitutional order.

The long Siege of Cuautla became one of the defining episodes of the war under José María Morelos. Royalist forces under Calleja tried to destroy the insurgent stronghold by surrounding the town and cutting off supplies. From February to May 1812, defenders endured hunger, bombardment, and repeated assaults. Morelos eventually led a breakout rather than surrendering. Even though the town itself could not be held, the episode greatly enhanced his reputation as the most capable insurgent commander after Hidalgo. Cuautla demonstrated that the rebellion could survive sustained military pressure and continue as a disciplined resistance rather than a brief uprising.

Following the collapse of Hidalgo’s campaign, insurgent leaders sought political structure as well as military survival. In August 1811, Ignacio López Rayón helped establish the Supreme Governing Junta at Zitácuaro. The body claimed to govern in the name of Ferdinand VII while effectively creating an autonomous political center for the rebellion. Though it struggled to maintain authority under military pressure and internal disagreements, the junta was an important milestone because it showed that the insurgency was evolving beyond spontaneous revolt into a movement capable of creating institutions, laws, and a vision of legitimate government distinct from viceregal rule.

After retreating north and being captured earlier in 1811, Miguel Hidalgo was tried, defrocked, and executed by firing squad in Chihuahua on 30 July. His death removed the charismatic figure who had ignited the rebellion, but it did not end the cause. Instead, Hidalgo became a martyr whose memory inspired later insurgents and gave the movement a powerful symbolic founder. Spanish authorities attempted to discourage further revolt by displaying the severed heads of Hidalgo and other leaders, yet the brutality of the punishment helped ensure that the uprising would be remembered as a national rather than merely local struggle.

The Battle of Calderón Bridge, fought east of Guadalajara, was decisive in breaking Hidalgo’s initial campaign. Although the insurgents vastly outnumbered the royalist army, they were poorly trained and unevenly armed. A shot that ignited rebel munitions helped turn the battle into a rout, allowing Félix María Calleja’s disciplined troops to win a major victory. The defeat shattered the momentum of the popular uprising, forced insurgent leaders to retreat north, and marked the end of the war’s opening mass-mobilization stage. From this point forward, the struggle increasingly shifted toward regional campaigns and more organized political leadership.

At Monte de las Cruces, in the mountains between Toluca and Mexico City, insurgent forces under Hidalgo and Ignacio Allende defeated royalist troops in a hard-fought battle. The victory placed the rebels within striking distance of the viceregal capital and represented the high-water mark of the first insurgent offensive. Yet despite this success, Hidalgo did not press into Mexico City, a decision that remains one of the most debated turning points of the war. The pause allowed royalist forces time to regroup and ultimately contributed to the collapse of the rebellion’s first phase.

Less than two weeks after the uprising began, Hidalgo’s rapidly growing insurgent force captured Guanajuato after attacking the fortified granary known as the Alhóndiga de Granaditas. Royalist officials and many Spanish residents had taken refuge inside, expecting the building to hold. Its fall gave the rebellion one of its first major victories and showed how quickly the movement could overwhelm colonial authority. At the same time, the killings that followed alarmed many elites and moderates, deepening fears of social revolution and shaping later divisions within the independence struggle.

In the early hours of 16 September 1810, priest Miguel Hidalgo y Costilla rang the church bell in Dolores and called on local residents to rise against Spanish colonial rule. The appeal, remembered as the Grito de Dolores, transformed a conspiracy that had been on the verge of discovery into an open rebellion. Hidalgo’s cry fused political resistance with demands for social change, especially against peninsular privilege and long-standing inequalities. Although the words were not preserved verbatim, the moment became the accepted beginning of the Mexican War of Independence and later the symbolic founding act of the Mexican nation.