Liberal leaders proclaimed the Plan de Ayutla in Guerrero to overthrow Antonio López de Santa Anna and call a constituent congress—commonly treated as the opening act of La Reforma.
After months of rebellion sparked by the Plan of Ayutla, Santa Anna resigned and left power, clearing the way for a Liberal-led government to begin major institutional and anti-clerical reforms.
Revolutionary leader Juan Álvarez became president after Santa Anna’s fall, bringing prominent liberals (including Benito Juárez) into national office and accelerating the Reform agenda.
The Ley Juárez abolished or restricted special jurisdictions (fueros) by ending separate military and ecclesiastical courts in many civil matters—an early, emblematic anti-clerical reform.
Finance minister Miguel Lerdo de Tejada’s Ley Lerdo ordered the forced sale of lands held by civil and ecclesiastical corporations (including much Church property and indigenous communal holdings), aiming to create a land market and strengthen state finances.
Mexico’s liberal Constitution of 1857 was promulgated, providing a constitutional framework for Reform principles (civil liberties and limits on corporate privilege and property), and sharpening conflict with conservative and ecclesiastical interests.
The Ley Iglesias sought to curb economic burdens on the poor by regulating fees charged for Catholic sacraments, further provoking Church–state conflict central to La Reforma.
Conservative forces under Félix María Zuloaga proclaimed the Plan of Tacubaya, seeking to nullify the 1857 Constitution and triggering a constitutional rupture that escalated into civil war.
The Reform War (also called the Three Years’ War) pitted Liberal constitutionalists against Conservative forces; the struggle became the proving ground for Reform laws and the future relationship between Church and state.
After Comonfort’s collapse following Tacubaya, Benito Juárez, as president of the Supreme Court, asserted the constitutional succession and established a Liberal government that ultimately operated from Veracruz during the conflict.
From Veracruz, Juárez’s Liberal government issued the Law of Nationalization of Ecclesiastical Properties, transferring Church property to the nation and intensifying the Reform program’s anti-clerical core.
A key Reform decree established civil marriage as the legally valid form, reducing the Church’s role in family law and embedding secular authority in everyday civil status.
Conservatives sought foreign backing by signing the Mon–Almonte Treaty with Spain, illustrating how the civil war over Reform measures internationalized diplomatic and financial stakes.
Juárez’s Liberal government signed the McLane–Ocampo Treaty with the United States, offering transit rights in exchange for support; it became controversial and ultimately was not ratified by the U.S. Senate.
The Liberal victory at Calpulalpan was the decisive military turning point that broke Conservative forces and effectively concluded the Reform War’s main campaign phase.
Following Liberal victories, Juárez returned to Mexico City, allowing the Reform program to be implemented more broadly from the national capital (despite continued pockets of resistance).
Facing fiscal crisis after years of war, Juárez announced a two-year suspension of payments on foreign debts—an act that helped precipitate European intervention.
France (after Spain and Britain initially joined pressure on Mexico) moved toward armed intervention in 1862, linking the post–Reform War fiscal crisis to a new phase of conflict that culminated in the Second Mexican Empire (1862–1867).
La Reforma: Liberal legislation and anti-clerical measures (1854–1867)
