Reform War
Mexico in 1858   Conservatives   Liberals   Independent
Date 17 December 1857 – 11 January 1861 (3 years, 3 weeks and 4 days) Location Mexico Result Liberal victory Nation's infrastructure and finances are left in ruins, Convention of London is signed by the United Kingdom, Spain, and France to guarantee debt payments Conservatives collaborate with the French during the subsequent second French intervention in Mexico to establish a monarchy
Belligerents
Liberals Supported by:  United States[1]	Conservatives Supported by:  Spain
Commanders and leaders
Benito Juárez Santos Degollado Ignacio Zaragoza Santiago Vidaurri Jesús González Ortega Emilio Langberg	Félix Zuloaga Miguel Miramón Leonardo Márquez Tomás Mejía Luis G. Osollo
Strength
78,570 1,000 Americans	54,889[citation needed]
Casualties and losses
8,713 103 Americans killed by Mexican liberals 4 American soldiers kidnapped in a cross-border raid by Mexican liberals and later executed	11,355[citation needed]

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The Reform War, or War of Reform (Spanish: Guerra de Reforma), also known as the Three Years' War (Spanish: Guerra de los Tres Años), and the Mexican Civil War,^[2] was a complex civil conflict in Mexico fought between Mexican liberals and conservatives with regional variations over the promulgation of Constitution of 1857. It has been called the "worst civil war to hit Mexico between the War of Independence of 1810–21 and the Revolution of 1910–20".^[3] Following the liberals' overthrow of the dictatorship of conservative Antonio López de Santa Anna, liberals passed a series of laws codifying their political program. These laws were incorporated into the new constitution. It aimed to limit the political power of the executive branch, as well as the political, economic, and cultural power of the Catholic Church. Specific measures were the expropriation of Church property; separation of church and state; reduction of the power of the Mexican Army by elimination of their special privileges; strengthening the secular state through public education; and measures to develop the nation economically.^[4]

The constitution had been promulgated on 5 February 1857 was to come into force on 16 September 1857. 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 Lerdo Law forced the sale of most of the Church's rural properties. 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. Controversy was further inflamed when the Catholic Church decreed the excommunication of civil servants who took a government-mandated oath upholding the new constitution, which left Catholic civil servants with the choice of losing their jobs or being excommunicated.^[5]

General Félix Zuloaga led army troops to the capital and closed congress and issued the Plan of Tacubaya on 17 December 1857. The constitution was nullified, President Comonfort was initially signed onto the plan and was retained in the presidency and given emergency powers. Some liberal politicians were arrested, including the president of the Supreme Court of Justice, Benito Juárez.^[6] Comonfort, hoping to establish a more moderate government, found himself triggering a civil war and began to back away from Zuloaga. On 11 January 1858, Comonfort resigned and went into exile. He was constitutionally succeeded by Juárez as president of the Supreme Court. 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. Initial choices for one side or the other often shifted over time. 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.

Both governments attained international recognition, the liberals by the United States and the conservatives by France, the United Kingdom, and Spain. The liberals negotiated the McLane–Ocampo Treaty with the United States in 1859. 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. The treaty failed to pass in the U.S. Senate, but the U.S. Navy still helped protect Juárez's government in Veracruz.

Liberals accumulated victories on the battlefield until conservative forces surrendered on 22 December 1860. Juárez returned to Mexico City on 11 January 1861 and held presidential elections in March.^[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.^[8]

After achieving independence in 1821, Mexico was alternatively governed by both liberal and conservative coalitions. 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. The brief liberal administration of Valentín Gómez Farías attempted to implement anti-clerical measures as early as 1833. The government closed church schools, assumed the right to make clerical appointments to the Catholic Church, and shut down monasteries.^[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.

In 1854 there was a liberal revolt, known as the Plan of Ayutla, against the dictatorship of Antonio López de Santa Anna. A coalition of liberals, including Benito Juárez, then governor of Oaxaca, and Melchor Ocampo of Michoacán overthrew Santa Anna, and the presidency passed on to the liberal caudillo Juan Alvarez.

Juan Álvarez assumed power in November 1855. 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.^[10]

Clashes in the cabinet led to the resignation of the radical Ocampo,^[11] but the administration was still determined to pass significant reforms. 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.^[12]

Further dissension within liberal ranks led to Álvarez's resignation and the more moderate Comonfort becoming president on 11 December and choosing a new cabinet. A constituent congress began meeting on 14 February 1856 and ratified the Juárez law. In June, another major controversy emerged over the promulgation of the Lerdo Law, named after the secretary of the treasury, Miguel Lerdo de Tejada. The law aimed at disentailing the collective ownership of real estate by the Roman Catholic Church and indigenous communities. It forced "civil or ecclesiastical institutions" to sell any land that they owned, with the tenants receiving priority and generous terms for purchasing the community-held land they cultivated. 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. Most of the lost indigenous lands community lands increased the size of large landed estates, haciendas.^[16][17]

The Constitution of 1857 was promulgated on 5 February 1857, and it incorporated both the Juárez and the Lerdo Laws. It was meant to take into effect on 16 September.^[18] On 17 March it was decreed that all civil servants had to publicly swear and sign and oath to it.^[19] The Catholic Church decreed excommunication for anyone that took the oath, and subsequently many Catholics in the government lost their jobs for refusing the oath.^[5]

Controversy over the constitution continued to rage, and Comonfort himself was rumored to be conspiring to form a new government. On 17 December 1857, General Félix Zuloaga proclaimed the Plan of Tacubaya, declaring the Constitution of 1857 nullified, and offered supreme power to President Comonfort, who was to convoke a new constitutional convention to produce a new document more in accord with Mexican interests. In response, congress deposed President Comonfort, but Zuloaga's troops entered the capital on the 18th and dissolved congress. 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.^[20]

The Plan of Tacubaya did not lead to a national reconciliation, and as Comonfort realized this he began to back away from Zuloaga and the conservatives. He resigned from the presidency and even began to lead skirmishes against the Zuloaga government, but after he was abandoned by most of his loyal troops, Comonfort left the capital on 11 January 1858, with the constitutional presidency having passed to the president of the Supreme Court, Benito Juárez. The Conservative government in the capital summoned a council of representatives that elected Zuloaga as president, and the states of Mexico proclaimed their loyalties to either the conservative Zuloaga or liberal Juárez governments. The Reform War had now begun.^[21]

President Juárez and his ministers fled from Mexico City to Querétaro. 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. Santiago Vidaurri and Manuel Doblado organized Liberal forces in the north and led a liberal coalition in the interior headquartered in the town of Celaya, Guanajuato. 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.^[22]

Juárez was in Jalisco's capital Guadalajara at this time, when on 13–15 March part of the army there mutinied and imprisoned him, threatening his life. 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. Conservatives took the silver mining center of Zacatecas on 12 April. Juárez reconstituted his regime in Veracruz, embarking from the west coast port of Manzanillo, crossing Panama, and arriving in Veracruz on 4 May 1858, making it the liberal capital.^[23]

Juárez made Santos Degollado the head of the Liberal armies, who went on to defeat upon defeat. Miramón defeated him in the Battle of Atenquique on 2 July. On 24 July, Miramón captured Guanajuato, and San Luis Potosi was captured by the conservatives on 12 September. Vidaurri was defeated at the Battle of Ahualulco on 29 September. By October the conservatives were at the height of their strength.^[24]

The liberals failed to take Mexico City on 14 October, but Santos Degollado captured Guadalajara on 27 October, after a thirty days siege that left a third of the city in ruins. This victory caused consternation at the conservative capital, but Guadalajara was taken back by Márquez on 14 December.^[25]

The failure of Zuloaga's government to produce a constitution actually led to a conservative revolt against him led by General Echegaray. He resigned in favor of Manuel Robles Pezuela on 23 December. On 30 December a conservative junta in Mexico City elected General Miguel Miramón as president.^[26]

President Miramón's most important military priority was now the capture of Veracruz, the liberals' stronghold. He left the capital on 16 February, leading the troops in person along with his minister of war. Aguascalientes and Guanajuato had fallen to the liberals. Liberal troops in the West were led by Degollado and headquartered in Morelia, which now served as a liberal arsenal. The conservatives fell ill with malaria, endemic in the Gulf Coast, and abandoned the siege of Veracruz by March 29.^[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.^{[citation needed]}

On 6 April, the Juárez government was recognized by the United States during the Buchanan administration. Miramón unsuccessfully attempted to besiege Veracruz in June and July. On 12 July, the liberal government nationalized the property of the Catholic church, and suppressed the monasteries and convents, the sale of which provided the liberal war effort with new funds, though not as much as had been hoped for since speculators were waiting for more stable times to make purchases.^[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. Negotiations broke down and hostilities resumed on the 12th after which Degollado was routed at the Battle of Las Vacas.^[29]

On 14 December 1859, Melchor Ocampo signed the McLane–Ocampo Treaty, which granted the United States perpetual rights to transport goods and troops across three key trade routes in Mexico and granted Americans an element of extraterritoriality. The treaty caused consternation among the conservatives and some liberals, the European press, and even members of Juárez's cabinet. The issue was rendered moot when the U.S. Senate failed to approve the treaty.^[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. The United States Navy however had orders to intercept it.^[31] Miramón arrived at Medellín on 2 March, and awaited Marín's attack in order to begin the siege. The U.S. steamer Indianola had been anchored near the fortress of San Juan de Ulúa, to defend Veracruz from attack.^[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.^[33] Miramón's effort to besiege Veracruz was abandoned on 20 March, and he arrived back in Mexico City on 7 April.

The conservatives also suffered defeats in the interior, losing Aguascalientes and San Luis Potosí before the end of April. Degollado was sent into the interior to lead the liberal campaign since their enemies had now exhausted their resources. He appointed José López Uraga as Quartermaster General^[34] Uraga split his troops and attempted to lure out Miramón to isolate him, but in late May Uraga then committed the strategic blunder of attempting to assault Guadalajara with Mirámon's troops behind him. The assault failed and Uraga was taken prisoner.^[35]

Miramón was routed on 10 August in Silao, Guanajuato, which resulted in his commander Tomás Mejía being taken prisoner, and Miramón retreated to Mexico City. In response to the disaster, Miramón resigned as president to seek a vote of confidence. The conservative junta elected him president again after a two days interregnum.^[36] By the end of August, liberals were preparing for a decisive final battle. Mexico City was cut off from the rest of the country. Guadalajara was surrounded by 17,000 liberal troops while the conservatives in the city only had 7,000. The conservative commander Castillo surrendered without firing a shot and was allowed to leave the city with his troops. General Leonardo Márquez was routed on 10 November, attempting to reinforce General Castillo without being aware of his surrender.^[37]

Miramón on 3 November convoked a war council, including in it prominent citizens to meet the crisis and by 5 November it was resolved to fight until the end. The conservatives were not struggling with a shortage of funds, due to looting the British legation of $700,000, but with increasing defections. Nonetheless, Miramon gained a victory when he attacked the liberal headquarters of Toluca on 9 December, in which almost all of their forces were captured.^[38] With the tide turning to liberal victories, Juárez rejected the McLane-Ocampo Treaty in November, while the treaty had previously been rejected in the U.S. Senate on 31 May and not ratified. Juárez had secured recognition from the U.S. government with the opening of negotiations with the United States, rejected outright sale of Mexican territory to the United States, and received aid from the U.S. Navy, in the end securing benefits to Mexico without actually concluding the treaty.

In early December as the tide of war had clearly turned to the liberals, Juárez signed the Law for the Liberty of Religious Worship on 4 December, the final step in the liberals' program to disempower the Roman Catholic Church by allowing religious tolerance in Mexico.^[39]

General González Ortega approached Mexico City with reinforcements. The decisive battle took place on 22 December, at Calpulalpan. The conservatives had 8,000 troops and the liberals 16,000. Miramón lost and retreated back towards the capital.^[40]

Another conservative war council agreed to surrender. The conservative government fled the city, and Miramón himself escaped to European exile. Márquez escaped to the mountains of Michoacán. The triumphant liberals entered the city with 25,000 troops on 1 January 1861, and Juárez entered the capital on 11 January.^[41]

After Zuloaga's coup, the conservative government was recognized swiftly by Spain and France. Neither conservatives nor liberals ever had official foreign troops as part of their respective armed forces. The conservative government signed the Mon-Almonte Treaty with Spain that promised to pay the Spanish government indemnities in exchange for aid. The liberals also sought foreign support from the United States. Mexico signed the McLane-Ocampo Treaty, which would have granted to the United States perpetual transit and extraterritorial rights in Mexico. This treaty was denounced by conservatives and some liberals, with Juárez countering that the territorial losses to the United States had occurred under the conservatives.^[42] With the liberal victory, Juárez's government was unable to meet foreign debt obligations, some of which stemmed from the Mon-Almonte Treaty. When Juárez's government suspended payments, the pretext was used to inaugurate the Second French Intervention in Mexico.

During the Reform War as the military stalemate continued, some liberals considered the idea of foreign intervention. The brothers Miguel Lerdo de Tejada and Sebastián were liberal politicians from Veracruz and had commercial connections with the United States. Miguel Lerdo, Juárez's Minister of Finance, attempted to negotiate a loan with the United States. He was reported to despair of Mexico's situation and saw some form of protection from the United States as the way forward and the way to prevent a resurgence of Spanish colonialism. Correspondence between Melchor Ocampo and Santos Degollado discussing Lerdo's attempt to negotiate a loan was captured and published by conservatives.^[43] Degollado was later to advocate mediation through the diplomatic corps in Mexico to end the conflict. Juárez flatly refused Degollado's call to resign, since Juárez saw that as turning over Mexico's future to European powers.^[44]

A French invasion and the establishment of the Second Mexican Empire followed almost immediately after the end of the Reform War, and key figures of the Reform War would continue to play roles during the rise and fall of the Empire.

While the main fighting in the Reform War was over by the end of 1860, guerilla conflict continued to be waged in the countryside. After the fall of the conservative government, General Leonardo Márquez remained at large, and in June, 1861, he succeeded in assassinating Melchor Ocampo. President Juárez sent the former head of his troops during the Reform War, Santos Degollado after Márquez, only for Márquez to succeed in killing Degollado as well.

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. Seeing the intervention as an opportunity to undo the Reform, conservative generals and statesmen who had played a role during the War of the Reform joined the French and a conservative assembly voted in 1863 to invite Habsburg Archduke Maximilian to become Emperor of Mexico.

The emperor, however, proved to be of liberal inclinations and ended up ratifying the Reform Laws. 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. The French eventually withdrew in 1866, leading the monarchy to collapse in 1867. 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. Leonardo Márquez once again escaped, this time to Cuba, living there until his death in 1913 and publishing a defense of his role in the empire.

• Cristero War
• Carlist Wars
• Second French Intervention in Mexico

• Connaughton, Brian, coord. México durante la Guerra de Reforma, tomo I: Iglesia, religión y leyes de reforma. Xalapa: Universidad Veracruzana 2011.
• Fowler, Will. La Guerra de Tres Años, 1857-1861: El conflicto del que nació el Estado laico mexicano. Mexico City: Crítica 2020.
• Fowler, Will. The Grammar of Civil War: A Mexican Case Study, 1857-1861. Lincoln: University of Nebraska Press 2022. ISBN 9781496230461
• Hamnett, Brian. Juárez. London: Longman 1994.
• Olliff, Donathan. Reforma Mexico and the United States: A Search for Alternatives to Annexation, 1854-1861. Tuscaloosa: University of Alabama Press 1981.
• Powell, T.G. "Priests and Peasants in Central Mexico: Social Conflict during La Reforma". Hispanic American Historical Review 57(1997): 296-313.
• Sinkin, Richard. The Mexican Reform, 1855-1876: A Study in Liberal Nation Building. Austin: Institute of Latin American Studies 1979.