Viceroy Juan Ruiz de Apodaca sends a force led by a royalist criollo officer, Augustin de Iturbide, to defeat Guerrero's army in Oaxacan in December 1820 in what is supposed to be the final government campaign against the insurgents.

Iturbide, a native of Valladolid, has gained renown for the zeal with which he had persecuted Hidalgo's and Morelos's rebels during the early independence struggle.

A favorite of the Mexican church hierarchy, Iturbide is the personification of conservative criollo values, devoutly religious, and committed to the defense of property rights and social privileges; he is also disgruntled at his lack of promotion and wealth.