The five Central American nations of Guatemala, El Salvador, Honduras, Nicaragua, and Costa Rica declare independence from the First Mexican Empire after being annexed the year prior.

The Mexican Empire was a constitutional monarchy and the first independent government of Mexico. It was also the only former viceroyalty of the Spanish Empire to establish a monarchy after gaining independence. The empire existed from 1821 to 1823, making it one of the few modern-era independent monarchies in the Americas. To distinguish it from the later Second Mexican Empire (1864–1867) under Emperor Maximilian, this historical period is commonly referred to as the First Mexican Empire. The empire was led by former Royal Spanish military officer Agustín de Iturbide, who ruled as Agustín I.