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.
Name of Mexico
In September 1821, the independence of Mexico was finally recognized by Spain, achieved through an alliance of royalist and revolutionary forces. The former tried to preserve the "status quo" of the vice-royalty, menaced by the liberal reforms taking place in Spain, through the establishment of an autonomous constitutional monarchy under an independence hero. Agustín was crowned and given the titles of: Agustin de Iturbide por la divina providencia y por el Congreso de la Nación, primer Emperador Constitucional de Mexico (Agustín de Iurbide First Constitutional Emperor of Mexico by Divine Providence and by the Congress of the Nation). The name chosen for the country was "Imperio Mexicano", "Mexican Empire". The empire collapsed in 1823, and the republican forces drafted a constitution the following year whereby a federal form of government was instituted. In the 1824 constitution, which gave rise to the Mexican federation, "Estados Unidos Mexicanos" (also "Estados-unidos mexicanos")—literally the "Mexican United States" or "Mexican United-States" (official English translation: "United Mexican States")—was adopted as the country's official name. The constitution of 1857 used the term "República Mexicana" ("Mexican Republic") interchangeably with "Estados Unidos Mexicanos"; the current constitution, promulgated in 1917, only uses the latter and "United Mexican States" is the normative English translation. The name "Mexican Empire" was briefly revived from 1863 to 1867 by the conservative government that instituted a constitutional monarchy for a second time under Maximilian of Habsburg.