Mexican War of Independence
Iturbide's assignment to the Oaxaca expedition coincided with a successful military coup in Spain against the monarchy of Ferdinand VII. The coup leaders, part of an expeditionary force assembled to suppress the independence movements in the Americas, had turned against the monarchy. They compelled the reluctant Ferdinand to reinstate the liberal Spanish Constitution of 1812 that created a constitutional monarchy. When news of the liberal charter reached Mexico, Iturbide perceived it both as a threat to the status quo and a catalyst to rouse the criollos to gain control of Mexico. Independence was achieved when conservative Royalist forces in the colonies chose to rise up against the liberal regime in Spain; it was an about-face compared to their previous opposition to the peasant insurgency. After an initial clash with Guerrero's forces, Iturbide assumed command of the royal army. At Iguala, he allied his formerly royalist force with Guerrero’s radical insurgents to discuss the renewed struggle for independence.
List of constitutions of Mexico
Since declaring independence in 1821, Mexico has adopted a number of constitutions or other documents of basic law with constitutional effects. Not all these can be considered constitutions, and not all of them enjoyed universal application. Those enacted in 1824, 1857, and 1917 are generally considered full-fledged, operational constitutions. The Constitution of 1824 established the framework of a federated republic, following the short-lived monarchy of Agustín de Iturbide (in 1821–22). The Constitution of 1857 was the framework set by Mexican liberals that incorporated particular laws into the constitution. The Constitution of 1917 was drafted by the faction that won the Mexican Revolution, known as the Constitutionalists for their adherence to the Constitution of 1857. It strengthened the anticlerical framework of the 1857 constitution, empowered the state to expropriate private property, and set protections for organized labor. The 1917 Constitution was significantly revised in 1992 under Carlos Salinas de Gortari, eliminating anticlerical restrictions and strengthening private property rights against the State.