Mexican War of Independence
Although Mexico gained its independence in September 1821, the marking of this historical event did not take hold immediately. The choice of date to celebrate was problematic, because Iturbide, who achieved independence from Spain, was rapidly created Emperor of Mexico. His short-lived reign from 1821–22 ended when he was forced by the military to abdicate. This was a rocky start for the new nation, which made celebrating independence on the anniversary of Iturbide's Army of the Three Guarantees marching into Mexico City in triumph a less than perfect day for those who had opposed him. Celebrations of independence during his reign were marked on September 27. Following his ouster, there were calls to commemorate Mexican independence along the lines that the United States celebrated in grand style its Independence Day on July 4. The creation of a committee of powerful men to mark independence celebrations, the "Junta Patriótica", organized celebrations of both September 16, to commemorate Hidalgo's grito and the start of the independence insurgency, and September 27, to celebrate actual political independence.
Spanish colonization of the Americas
In 1809 the first declarations of independence from Spanish rule occurred in the Viceroyalty of New Granada. The first two were in present-day Bolivia at Sucre (May 25), and La Paz (July 16); and the third in present-day Ecuador at Quito (August 10). In 1810 Mexico declared independence, with the Mexican War of Independence following for over a decade. In 1821 Treaty of Córdoba established Mexican independence from Spain and concluded the War. The Plan of Iguala was part of the peace treaty to establish a constitutional foundation for an independent Mexico.