Key Facts
- Duration
- 1846–1863
- Peak population
- ~8.6 million
- Territory lost to USA
- Approximately half of national territory (1848)
- Governing document
- Constitution of 1857 (superseding 1824 constitution)
- Civil conflict
- Reform War, 1857–1860
Imperial Zenith Metrics
Historical Trajectory
Phase I: Rise
The Second Federal Republic emerged in 1846 when the Centralist Republic collapsed at the outset of the Mexican–American War, prompting restoration of the federalist Constitution of 1824. The republic faced immediate military pressure from the United States, and the war concluded in 1848 with Mexico compelled to cede roughly half its territory under the Treaty of Guadalupe Hidalgo. A brief period of moderate, stable governance followed before conservative factions reasserted control.
Phase II: Zenith
The Liberal movement's overthrow of Santa Anna's final dictatorship in 1853 launched La Reforma, enacting sweeping constitutional changes including separation of church and state and nationalization of Catholic Church lands. The Constitution of 1857 codified these reforms, representing the most substantial restructuring of Mexican governance to that point. Liberal president Benito Juárez led the republic through the subsequent Reform War, emerging victorious in 1860 and consolidating Liberal political dominance.
Phase III: Decline
A fiscal crisis prompted Juárez to suspend foreign debt payments, giving the French Second Empire a pretext to intervene militarily in 1861. French forces suffered an initial defeat at the Battle of Puebla in 1862, delaying their advance by a year. Reinforced French troops eventually compelled Juárez to evacuate Mexico City in June 1863. A French-arranged Assembly of Notables then proclaimed the Second Mexican Empire under Maximilian of Habsburg in July 1863, ending the Second Federal Republic.
Notable Imperial Reigns
Selected rulers mapping the empire’s trajectory