Mexican Reform War

The Reform War was fought in Mexico from December 1857 to January 1861 between Liberal and Conservative factions after Mexico's new 1857 Constitution, which stripped the Catholic Church of much of its property and legal privilege and separated church from state, provoked fierce Conservative and clerical opposition, including a Church threat of excommunication against anyone who swore the constitutional oath. Conservative general Felix Zuloaga issued the Plan of Tacubaya on 17 December 1857 to nullify the constitution, forcing the Liberal president Benito Juarez to flee and establish a rival government at Veracruz, from which Liberal forces under commanders including Santos Degollado and Ignacio Zaragoza eventually gained the upper hand despite early Conservative battlefield successes. The war turned decisively in the Liberals' favor at the Battle of Calpulalpan on 22 December 1860, and Juarez returned in triumph to Mexico City on 11 January 1861 to hold new presidential elections. The war secured Mexico's secular, constitutional state but left its treasury devastated, a weakness that directly enabled the Conservative-backed French intervention and the short-lived Second Mexican Empire that followed within the same decade.