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.
Latin America–United States relations
Texas, which had been settled by colonies of Americans, fought a successful war for independence from Mexico in 1836. Mexico refused to recognize the independence and warned that annexation to the United States meant war. Annexation came in 1845 and the Mexican–American War began in 1846. The American military was easily triumphant. The result was the Mexican Cession of Santa Fe de Nuevo México and Alta California. About 60,000 Mexicans remained in the territories and became US citizens. France took advantage of the American Civil War (1861–65), using its army to take over Mexico. Due to defeats in Europe, France pulled out troops, leaving the Imperialists and Maximilian I of Mexico to face defeat from the Benito Juarez-led Republicans (backed by the US).