In early 1822, the last Spanish stronghold in Mexico was the Fort of San Juan de Ulua - located on a small island off the coast of Veracruz.

When Captain General José Antonio Echávarri, the captain-general of the local provinces, arrived in Veracruz, he approved of the plan; agreeing to join Santa Anna in the scheme.

[1] When Iturbide learned of the rebellion, Santa Anna was declared a traitor, deprived of his rank, and pardon was offered to any of his followers who would return their allegiance to the Empire within an allotted time.

[2] Vicente Guerrero and Nicolas Bravo, defected from the ranks of the imperialists, and proceeded to Chilapa on January 5, 1823, to join the revolution, but experienced a disastrous defeat at Almolonga.

[4] On the following day, the 4th Cavalry Regiment joined the rebels, and later that night, the remaining grenadiers on horseback from the Emperor's guard also defected.

This left Iturbide with only the forces that remained loyal to him in Ixtapaluca, where he was stationed to cut off communication between the rebels in Puebla and prevent further defections.

Iturbide, wanting to avoid the conflict, sent the military commander of the capital, Brigadier Manuel Gómez Pedraza to Santa Marta, where General Marquis Antonio de Vivanco had located his headquarters, to enter into an agreement with the pronounced.