French intervention in Mexico The second French intervention in Mexico ( ) , also known as the Maximilian Affair , Mexican Adventure , the War of the French Intervention or the Franco - Mexican War , was an invasion of Mexico by the Second French Empire , supported in the beginning by the United Kingdom and Spain . It followed President Benito Juárez ' s suspension of interest payments to foreign countries on 17 July 1861 , which angered Mexico ' s major creditors : Spain , France and Britain . Emperor Napoleon III of France was the instigator , justifying military intervention by claiming a broad foreign policy of commitment to free trade . For him , a friendly government in Mexico would ensure European access to Latin American markets . Napoleon also wanted the silver that could be mined in Mexico to finance his empire . Napoleon built a coalition with Spain and Britain while the U . S . was engaged in a full - scale civil war . The three European powers signed the Treaty of London on 31 October , to unite their efforts to receive payments from Mexico . On 8 December the Spanish fleet and troops arrived at Mexico ' s main port , Veracruz . When the British and Spanish discovered however that France planned to seize all of Mexico , they quickly withdrew . The subsequent French invasion resulted in the Second Mexican Empire , which was supported by the Roman Catholic clergy , many conservative elements of the upper class , and some indigenous communities ; the presidential terms of Benito Juárez ( 1858 – 71 ) were interrupted by the rule of the Habsburg monarchy in Mexico ( 1864 – 67 ) . Conservatives , and many in the Mexican nobility , tried to revive the monarchical form of government ( see : First Mexican Empire ) when they helped to bring to Mexico an archduke from the Royal House of Austria , Maximilian Ferdinand , or Maximilian I who was married to Charlotte of Belgium , who changed her name to Carlota when she and Maximillian were sent to Trieste . France had various interests in this Mexican affair , such as seeking reconciliation with Austria , which had been defeated during the Franco - Austrian War of 1859 , counterbalancing the growing American Protestant power by developing a powerful Catholic neighboring empire , and exploiting the rich mines in the north - west of the country . 1862 : Arrival of the French . The British , Spanish and French fleets arrived at Veracruz , between 8 and 17 December 1861 intending to pressure the Mexicans into settling their debts . The Spanish fleet seized San Juan de Ulúa and subsequently the capital Veracruz on 17 December . The European forces advanced to Orizaba , Cordoba and Tehuacán as it had been agreed in the Convention of Soledad . The city of Campeche surrendered to the French fleet on 27 February , and a French army , commanded by General Lorencez , arrived on 5 March . When the Spanish and British realised the French ambition to conquer Mexico , they withdrew their forces on 9 April , their troops leaving on 24 April . In May , the French man - of - war " Bayonnaise " blockaded Mazatlán for a few days . The French army suffered an initial defeat in the Battle of Puebla on 5 May 1862 ( commemorated with the Cinco de Mayo holiday ) against the Mexican forces commanded by General Ignacio Zaragoza . The pursuing Mexican army was then contained by the French at Orizaba , Veracruz , on 14 June . More French troops arrived on 21 September , and General Bazaine arrived with more reinforcements on 16 October . Tampico , Tamaulipas , was occupied by the French on 23 October , with Xalapa , Veracruz , taken peacefully on 12 December . 1863 : The French take the capital . The French bombarded Veracruz on 15 January 1863 . Then , on 16 March , General Forey and the French Army began the siege of Puebla . On 30 April , the French Foreign Legion earned its fame in the Battle of Camarón when the small infantry patrol unit , led by a one - handed Captain named Jean Danjou , numbering 62 soldiers and three officers was attacked and besieged by Mexican infantry and cavalry units numbering three battalions , about 3000 men , and was forced to make a defence in Hacienda Camarón . Danjou was mortally wounded in the defense of the hacienda , and the last of his men mounted a glorious bayonet attack fighting to nearly the last man , leaving three survivors . To this day , ' Camerone Day ' is still the most important day of celebration for Legionnaires . The French army of General François Achille Bazaine defeated the Mexican army led by General Comonfort in their attempt to relieve the siege of Puebla , at San Lorenzo , to the south of Puebla . Puebla surrendered to the French shortly afterward , on 17 May . On 31 May , President Juárez fled the city with his cabinet , retreating northwards to Paso del Norte and later to Chihuahua , where the government - in - exile remained until 1867 , taking the treasure of the state with them . French troops under Bazaine entered Mexico City on 7 June 1863 . The main army entered the city three days later led by General Forey . General Almonte was appointed the provisional President of Mexico on 16 June , by the Superior Junta ( which had been appointed by Forey ) The Superior Junta with its 35 members met on 21 June , and proclaimed a Catholic Empire on 10 July . The crown was offered to Maximilian , following pressures by Napoleon . Maximilian accepted the crown on 3 October , at the hands of the Comisión Mexicana , sent by the Superior Junta . 1864 : Arrival of Maximilian . On 28 and 31 March 1864 , men from the French man - of - war " Cordelière " tried to take Mazatlán , but were initially repelled by Mexicans commanded by Colonel Gaspar Sánchez Ochoa . The French under Bazaine occupied Guadalajara on 6 January 1864 , and troops under Douay occupied Zacatecas on 6 February . Further decisive French victories continued with the fall of Acapulco on 3 June , occupation of Durango on 3 July , and the defeat of republicans in the states of Sinaloa and Jalisco in November . Maximilian formally accepted the crown on 10 April , signing the , and landed at Veracruz on 28 May ( or possibly 29 May ) 1864 in the SMS " Novara " . He was enthroned as Maximilian , Emperor of Mexico . In reality , puppet monarch of the Second French Empire . Maximilian of Habsburg was very much the product of the progressive ideas in vogue in the West at the time . He favoured the establishment of a limited monarchy sharing powers with a democratically - elected congress and inspired laws that abolished child labour , limited working hours , and abolished a system of land tenancy that virtually amounted to serfdom among the Indians . This was too liberal to please Mexico ' s conservatives , while the liberals refused to accept a monarch , leaving Maximilian with few enthusiastic allies within Mexico . On Sunday , 13 November 1864 , three French men - of - war ( " Victoire " , " D ' Assas " and " Diamante " ) shelled Mazatlán 13 times , and Imperial Mexican forces under Manuel Lozada entered and captured the city . 1865 : Beginning of Republican victories . The French continued with victories in 1865 , with Bazaine capturing Oaxaca on 9 February ( defeating the city ' s defenders under General Porfirio Díaz ) . The French fleet landed soldiers who captured Guaymas on 29 March . However on 11 April , republicans defeated Imperial forces at Tacámbaro in Michoacán . In April and May the republicans had many forces in the states of Sinaloa and Chihuahua . Most towns along the Rio Grande were also occupied by republicans . The Belgian volunteers were defeated by the republicans at the Second Battle of Tacámbaro on 11 July . The decree known as the " Black Decree " was issued by Maximilian on 3 October , which threatened any Mexican captured in the war with immediate execution . This was the later basis of his own execution . Several high - ranking republican officials were executed under this order on 21 October . American perspective . American President Abraham Lincoln had supported the republicans under Juárez , but was unable to intervene due to the American Civil War . Immediately after the end of the war , in 1865 , United States Army General Philip Sheridan , under the supervision of President Andrew Johnson and General Ulysses S . Grant , assembled 50 , 000 troops , and dispatched them to the border between Mexico and the United States . There , his corps ran patrols to visibly threaten intervention against the French , and also supplied weapons to Juárez ' s forces . The United States House of Representatives unanimously passed a resolution on 4 April 1864 which opposed the establishment of the Mexican monarchy , but consideration of the resolution was postponed by the United States Senate . On 12 February 1866 , in accordance with the Monroe Doctrine , the US requested the French withdraw their forces from Mexico ; while moving soldiers to positions along the Rio Grande , and set up a naval blockade to prevent French reinforcements from landing . The US officially protested to Austria about the Austrian volunteers in Mexico on 6 May . 1866 : French withdrawal and Republican victories . In 1866 , choosing Franco - American relations over his Mexican monarchy ambitions , Napoleon III announced the withdrawal of French forces beginning 31 May . The Republicans won a series of crippling victories taking immediate advantage of the end of French military support to the Imperial troops , occupying Chihuahua on 25 March , taking Guadalajara on 8 July , further capturing Matamoros , Tampico and Acapulco in July . Napoleon III urged Maximilian to abandon Mexico and evacuate with the French troops . The French evacuated Monterrey on 26 July , Saltillo on 5 August , and the whole state of Sonora in September . Maximilian ' s French cabinet members resigned on 18 September . The Republicans defeated imperial troops in the Battle of Miahuatlán in Oaxaca in October , occupying the whole of Oaxaca in November , as well as parts of Zacatecas , San Luis Potosí and Guanajuato . On 6 December the Austrian and Belgian volunteers disbanded and were supposed to join the Mexican Army ; however , 3500 of the 4648 volunteers did not enlist , and tried to flee the country . On 13 November , Ramón Corona and the French agreed to terms for the withdrawal of Mazatlán . At noon , the European invaders boarded three men - of - war , " Rhin " , " Marie " and " Talisman " and departed . 1867 : Republicans take the capital . The Republicans occupied the rest of the states of Zacatecas , San Luis Potosí and Guanajuato in January . The French evacuated the capital on 5 February . On 13 February 1867 , Maximilian withdrew to Querétaro . The Republicans began a siege of the city on 9 March , and Mexico City on 12 April . An imperial sortie from Querétaro failed on 27 April . On 11 May , Maximilian resolved to attempt an escape through the enemy lines . He was , however , intercepted before he could carry out this plan on 15 May and , following a court - martial , was sentenced to death . Many of the crowned heads of Europe and other prominent figures ( including liberals Victor Hugo and Giuseppe Garibaldi ) sent telegrams and letters to Mexico pleading for Maximilian ' s life to be spared , but Juárez refused to commute the sentence , believing that it was necessary to send a message that Mexico would not tolerate any government imposed by foreign powers . Maximilian was executed on 19 June ( along with his generals Miguel Miramón and Tomás Mejía ) on the Cerro de las Campanas , a hill on the outskirts of Querétaro , by the forces loyal to President Benito Juárez , who had kept the federal government functioning during the French intervention . Mexico City surrendered the day after Maximilian was executed . The republic was restored , President Juárez was returned to power in the national capital , yet there was little change in policy given that Maximilian had upheld most of Juárez ' s liberal reforms . After the victory , the Conservative party was so thoroughly discredited by its alliance with the invading French troops that it effectively ceased to exist , and the Liberal party was almost unchallenged as a political force during the first years of the " restored republic " . In 1871 , however , Juárez was re - elected to yet another term as president in spite of a constitutional prohibition of re - elections , provoking one of the losing candidates , Porfirio Díaz ( a Liberal general and a hero of the French war , but increasingly conservative in outlook ) to launch a rebellion against the president . Supported by conservative factions within the Liberal party , the attempted revolt ( the so - called Plan de la Noria ) was already at the point of defeat when Juárez died in office on 19 July 1872 , making it a moot point . Díaz ran against interim president Sebastián Lerdo de Tejada , lost the election , and retired to his hacienda in Oaxaca . Four years later , in 1876 , when Lerdo himself ran for re - election , Díaz launched a second , successful revolt ( the Plan de Tuxtepec ) and captured the presidency , which he effectively held through eight terms until 1911 . French expeditionary force , 31 December 1862 . At its peak in 1863 , the French expeditionary force counted 38 , 493 men ( which represented 6 . 25 % of the French army ) . 6 , 654 French died , including 4 , 830 from disease . Among these losses , 1 , 918 of the deaths were from the regiment of the French Foreign Legion . Général de Division Forey Not yet arrived : 16 October 1864 14 November 1864 16 December 1864 27 January 1865 15 April 1866 16 July 1866