Iturbide's popularity reached its peak on May 18, 1822, when public demonstrations called for him to become emperor in the absence of a European royal willing to assume the throne.

The empire's brief existence was marked by challenges, including disputes over its legitimacy, conflicts between the Congress and the emperor, and a bankrupt national treasury.

However, by December of the same year, he began to lose the support of the Mexican Army, which rebelled in favor of restoring the Congress and its democratic powers.

The newly constituted movement involved three principles, or "guarantees": that Mexico would be an independent constitutional monarchy governed by a Spanish prince; that Americanos, that is all Mexicans regardless of ethnic category and those born in Spain would henceforth enjoy equal rights and privileges; and that the Roman Catholic Church would retain its privileges and position as the official and exclusive religion of the land.

These Three Guarantees formed the core of the Plan of Iguala, the blueprint which, by combining the goal of independence and a constitution with the preservation of Catholic monarchy and Roman Catholicism, brought together all Mexican factions.

On the night of 18 May, the 1st infantry regiment, stationed at the ex Convent of San Hipólito, and led by sergeant Pio Marcha began a public demonstration in favor of Iturbide being made emperor.

[10] Congress, nonetheless resigned itself to the situation, and a plan to establish a constitutional monarchy united both conservatives and liberals at a time when it was uncertain which form of government would be best for independent Mexico.

To remedy the financial difficulties, the Mexican government prohibited the exportation of money, and exacted a forced loan of 600,000 pesos in Mexico City, Puebla, Guadalajara, and Veracruz.

During this time, a council of state was also formed, being made up of thirteen members selected by the Emperor from a list of thirty one nominees submitted by congress.

They were to keep track of seditious plots, but also in cases of murder, robbery or injury, and with the permission of the district captain general, the courts would be allowed to disregard statutes that would interfere with quickly carrying out judicial processes.

[18] Iturbide's greatest enemy in congress was deputy Servando Teresa de Mier, a staunch republican, who would often ridicule the Emperor and his pageantry.

The conspirators, claiming that Iturbide's election was illegal, plotted to rise up in the capital, move the congress to Texcoco and declare the establishment of a Republic.

On 26 and 27 August, fifteen deputies suspected of being involved with the plot, including Mier, Carlos Maria Bustamante, Francisco Tagle, Jose del Valle, and José Joaquín de Herrera were arrested.

Secretary of Interior Relations, Andrés Quintana Roo replied that by virtue of the Spanish Constitution of 1812, the government had the authority to arrest deputies suspected of being involved in a treasonous conspiracy, and that congress would remain informed on the results of the ongoing investigation.

[23] On October 16, Iturbide gathered several deputies and generals at his home, and began to discuss the measure of dissolving congress under the pretext that it did not as it stood, proportionally represent the provinces.

The following day, members of the council of state, the generals based in Mexico City, and more than forty deputies gathered at Iturbide's home for a conference regarding the problems with congress.

[27] Iturbide's pretext was that congress had accomplished nothing in the eight months it had been in session, work on a constitution had not begun despite that being the main purpose for its convocation, and that the matters of justice and finance had been completely neglected.

[28] To replace congress, Iturbide established a National Institutional Junta made up of forty five members, chosen from among friendly deputies.

Iturbide entrusted the body with writing up regulations for producing a new congress, but also began to focus on the grave financial issues that the Empire was facing.

[29] Iturbide also began to issue paper currency, and on 20 December, the government authorized the printing of four million pesos worth of banknotes, in denominations of one, two, and ten.

Iturbide himself went to Veracruz to dismiss Santa Anna from his command, not overtly however but rather under the pretext of simply moving him to a different post in Mexico City.

However, Santa Anna suspecting his ruin, instead took command of his troops and in December, 1822 started a rebellion in favour of a republican form of government.

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

The insurrection was mostly being suppressed at this time, Victoria being held in check at Puente del Rey, and Santa Anna still confined at Veracruz.

On 1 February 1823 a junta including many military chiefs, and the liberal diplomat Miguel Santa María met in Veracruz to proclaim the Plan of Casa Mata.

[35] The territory of the Mexican Empire corresponded to the borders of Viceroyalty of New Spain, excluding the Captaincies General of Cuba, Santo Domingo and the Philippines.