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.
Guerrero
Peoples of the territory of Guerrero immediately supported the cause of Miguel Hidalgo y Costilla which would culminate with the Independence of Mexico. During the first part of the Mexican War of Independence, José María Morelos fought on the side of Miguel Hidalgo in the southern part of Mexico, including the Acapulco area and the Costa Grande. However, the insurgents were never able to take the port. They were able to take control of territories in the center of the state. Morelos took Chilpancingo and set up the Congress of Anáhuac, which would publish the document "Sentimentos de la Nación" on 6 November 1813. The Congress of Anáhuac also approved the Act of Independence written by Carlos María Bustamante. Later, the Mexican flag was designed and first sewn in Iguala, after Agustín de Iturbide and Vicente Guerrero joined forces under the Plan of Iguala to end the war in 1821.