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.
Centralist Republic of Mexico
Months later, Antonio López de Santa Anna, in response to the declaration of independence, threatened to send in the troops if it was not reversed while also assuring the Tabasco authorities that Federalism would soon be reinstated. This combined threat and promise culminated in the reinstatement of Tabasco into the Mexican Republic on December 2, 1842. But four years later, Tabasco again declared its independence in November 1846 as a protest to the lack of Central government assistance in resisting the American occupation of its coast earlier that same year.