Central America under Mexican rule

From January 1822 to July 1823, the Captaincy General of Guatemala, a former Spanish colony, was controlled by the First Mexican Empire, and briefly, the Supreme Executive Power—the provisional government that succeeded Mexican imperial rule. The captaincy general consisted of the provinces of Chiapas, Costa Rica, El Salvador, Guatemala, Honduras, and Nicaragua—the six southernmost provinces of the Mexican Empire. The incorporation of Central America brought Mexico to the height of its territorial extent.

Only two months after the Act of Independence of Central America was signed in September 1821, Regent of Mexico Agustín de Iturbide, who later became the emperor of Mexico in May 1822, made a formal request to the Consultive Junta of Guatemala City—the Central American government—to accept annexation to the Mexican Empire. His request was accepted on 5 January 1822. Despite the acceptance by the Guatemalan-based government, El Salvador, Costa Rica, and parts of Nicaragua resisted Mexican annexation, and Mexican and allied Guatemalan soldiers were mobilized to subjugate those regions.

Mexican and allied Guatemalan forces were commanded by Brigadier General Vicente Filísola, who was serving as the captain general of the Central American provinces. Just over a year was spent on a military campaign that defeated the resistance and ended in the annexation of El Salvador in February 1823. In Costa Rica, the government declared independence from Mexico in October 1822, however, a coup d'état by pro-Mexican monarchists in March 1823 led to the outbreak of a civil war. The Ochomogo War of April 1823 deposed the monarchist government and reestablished the secessionist government. Meanwhile, a rebellion in Nicaragua led by José Anacleto Ordóñez sought to overthrow the incumbent Nicaraguan government.

Before Filísola could continue to Nicaragua and Costa Rica after his victory in El Salvador, Iturbide was forced to abdicate the Mexican imperial throne and go into exile, and a provisional government was established after the abolition of the monarchy. As a result, Filísola abandoned his orders to continue the conquest of Central America and convened a congress of Central American political leaders to determine the future of Central America. On 1 July 1823, the Central American congress declared independence from Mexico and established the United Provinces of Central America, later known as the Federal Republic of Central America, which existed until its dissolution in 1841 after the First and Second Central American Civil Wars. Not all of Central America chose to become independent, however, as Chiapas remained a part of Mexico and is now one of the country's 31 states.