Predictably there was fierce opposition from Conservatives and the Catholic Church over its anti-clerical provisions, but there were also moderate liberals, including President Ignacio Comonfort, who considered the constitution too radical and likely to trigger a civil war.

The measure was not exclusively aimed at the Catholic Church, but also Mexico's indigenous peoples, which were forced to sell sizeable portions of their communal lands.

The nation's states subsequently chose to side with either the Mexico City-based government of Zuloaga or that of Juárez, which established itself at the strategic port of Veracruz.

The first year of the war was marked by repeated conservative victories, but the liberals remained entrenched in the nation's coastal regions, including their capital at the port of Veracruz, which gave them access to vital customs revenue that could fund their forces.

If ratified the treaty would have given the liberal regime cash, but it would have also granted the United States perpetual military and economic rights on Mexican territory.

[7] Although the conservative forces lost the war, guerrillas remained active in the countryside and later joined the upcoming French intervention to help establish the Second Mexican Empire.

The original Constitution of 1824 established the federalist system championed by the liberals, with the states holding sovereign power and the central government being weak.

[9] The ensuing backlash would result in Gómez Farías's government being overthrown and conservatives established a Centralist Republic in 1835 that lasted until the outbreak of the Mexican–American War in 1846.

His cabinet was radical and included the prominent liberals Benito Juárez, Miguel Lerdo de Tejada, Melchor Ocampo, and Guillermo Prieto, but also the more moderate Ignacio Comonfort.

On 23 November 1855, the Juárez Law, named after the Minister of Justice, substantially reduced the jurisdiction of military and ecclesiastical courts which existed for soldiers and clergy.

The law sought to undermine the economic power of the Church and to force create a class of yeoman farmers of indigenous community members.

[13][14] The law was envisioned as a way to develop Mexico's economy by increasing the number of indigenous private property owners,[15] but in practice the land was bought up by rich speculators.

The following day, Comonfort accepted the Plan of Tacubaya, and released a manifesto making the case that more moderate reforms were needed under the current circumstances.

General Zuloaga, knowing the strategic importance of the Gulf Coast state of Veracruz, tried to win over its governor, Gutierrez Zamora, who however affirmed his support for the government of Juárez.

On 10 March 858, liberal forces under Anastasio Parrodi, governor of Jalisco, and Leandro Valle lost the Battle of Salamanca, which opened up the interior of the country to the conservatives.

Liberal minister and fellow prisoner Guillermo Prieto dissuaded the hostile soldiers from shooting Juárez, an event now memorialized by a statue.

As rival factions struggled to control the city, Juárez and other liberal prisoners were released on agreement after which Guadalajara was fully captured by conservatives by the end of March.

[27] Liberal General Degollado made another attempt on Mexico City in early April and was routed in the Battle of Tacubaya by Leonardo Márquez.

Márquez captured a large amount of war materiel and gained infamy for including medics among those executed in the aftermath of the battle.

[28] Miramón met the liberal forces in November at which a truce was declared and a conference was held on the matter of the Constitution of 1857 and the possibility of a constituent congress.

[30] Miramón was preparing another siege of Veracruz, leaving the conservative capital of Mexico City on 8 February, leading his troops in person along with his war minister, hoping to rendezvous with a small naval squadron led by General Tomás Marín who was disembarking from Havana.

[32] On 6 March, Marín's squadron arrived in Veracruz, and was captured by U.S. Navy Captain Joseph R. Jarvis in the Battle of Antón Lizardo The ships were sent to New Orleans, along with the now imprisoned General Marin, depriving the conservatives of an attack force and the substantial artillery, guns, and rations that they were carrying onboard for delivery to Miramón.

The brothers Miguel Lerdo de Tejada and Sebastián were liberal politicians from Veracruz and had commercial connections with the United States.

Correspondence between Melchor Ocampo and Santos Degollado discussing Lerdo's attempt to negotiate a loan was captured and published by conservatives.

Having been influenced by Mexican monarchist exiles, using Juárez's suspension of foreign debts as a pretext, and with the American Civil War preventing the enforcement of the Monroe Doctrine, Napoleon III invaded Mexico in 1862, and sought local help in setting up a monarchical client state.

Former liberal president Ignacio Comonfort, who had played such a key role in the outbreak of the Reform War, was killed in action that year, having returned to the country to fight the French, and having been given a military command.

Former conservative president during the Reform War Manuel Robles Pezuela was also executed in 1862 by the Juárez government for attempting to help the French.

Regardless, the liberal government of Benito Juárez still resisted and fought the French and Mexican Imperial forces with the backing of the United States, which since the end of the American Civil War could now once again enforce the Monroe Doctrine.

Former President Miguel Miramón and conservative general Tomas Mejía would die alongside the Emperor, being executed by a firing squad on 19 June 1867.

Santiago Vidaurri, once Juárez's commander in the north during the Reform War, had actually joined the imperialists, and was captured and executed for his betrayal on 8 July 1867.