Three essential articles made up this proposal: (1) the preservation of the Roman Catholic Church, with the exclusion of other forms of religion; (2) the absolute independence of Mexico under the government of a moderate monarchy with some member of the reigning house of Spain upon the throne; and (3) the amicable union of Spaniards and Mexicans. These three clauses were called the "three guaranties." When the national Mexican flag was devised later, its colors represented these three articles of the national faith--white for religious purity, green for union, and red for independence. The army of Yturbide was known as the army of the three guaranties. Upon this basis the contest was resumed. It found favor in many parts of Mexico, and the independent troops, with their chiefs, very generally gave in their adherence at once to the Plan of Iguala. As soon as the viceroy could recover from his surprise on waking up one day to find a brigadier of his own troops concerting a revolution, he issued manifestoes against the undertaking, and at once set about raising an army of six thousand men, which advanced but slowly to the field of action in the south, where the troops of the late brigadier had joined the insurgent forces. This gave time for the Independents to collect together the various forces of Bustamente and other chiefs of their way of thinking. Valladolid was compelled to capitulate for the third or fourth time in twenty years; afterwards Querétaro, and, finally, Puebla, which, besieged by the troops of Bravo and Herrera, surrendered to Yturbide, who made a triumphal entry into the city on the 2d of August, 1821. This was the first of the sieges which the City of the Angels has sustained, its position with regard to the capital exposing it to every ill wind that blows in that direction. The viceroy, Apodaca, hearing of the rapid triumphs of the insurgents, adopted defensive measures. He established a permanent Junta of war, stopped the liberty of the press, and decreed the enforced enlistment of all men between sixteen and sixty. But desertions were constant, the public spirit was aroused against government, and except that the pure Spaniards were in favor of it, all social classes were decided to overthrow the old regime. Even the garrison of Mexico, losing faith in the viceroy, conspired against him. A meeting inspired by these discontented troops invaded the viceregal palace, and informed Apodaca that his charge was at an end. Francisco Novella, sub-inspector of artillery, was hastily set up into his place; the deposed viceroy left the capital next day with his family, and returned, with such haste as they could bring to pass, to Spain.