The Uruguayan War (10 August 1864 – 20 February 1865) was fought between Uruguay's governing Blanco Party and an alliance consisting of the Empire of Brazil and the Uruguayan Colorado Party, covertly supported by Argentina. Since its independence, Uruguay had been ravaged by intermittent struggles between the Colorado and Blanco factions, each attempting to seize and maintain power in turn. The Colorado leader Venancio Flores launched the Liberating Crusade in 1863, an insurrection aimed at toppling Bernardo Berro, who presided over a Colorado–Blanco coalition (fusionist) government. Flores was aided by Argentina, whose president Bartolomé Mitre provided him with supplies, Argentine volunteers and river transport for troops.
The fusionism movement collapsed as the Colorados abandoned the coalition to join Flores' ranks. The Uruguayan Civil War quickly escalated, developing into a crisis of international scope that destabilized the entire region. Even before the Colorado rebellion, the Blancos within fusionism had sought an alliance with Paraguayan dictator Francisco Solano López. Berro's now purely Blanco government also received support from Argentine federalists, who opposed Mitre and his Unitarians. The situation deteriorated as the Empire of Brazil was drawn into the conflict. Almost one fifth of the Uruguayan population were considered Brazilian. Some joined Flores' rebellion, spurred by discontent with Blanco government policies that they regarded as harmful to their interests. Brazil eventually decided to intervene in the Uruguayan affair to reestablish the security of its southern frontiers and its regional ascendancy.
In April 1864, Brazil sent Minister Plenipotentiary José Antônio Saraiva to negotiate with Atanasio Aguirre, who had succeeded Berro in Uruguay. Saraiva made an initial attempt to settle the dispute between Blancos and Colorados. Faced with Aguirre's intransigence regarding Flores' demands, the Brazilian diplomat abandoned the effort and sided with the Colorados. On 10 August 1864, after a Brazilian ultimatum was refused, Saraiva declared that Brazil's military would begin exacting reprisals. Brazil declined to acknowledge a formal state of war, and for most of its duration, the Uruguayan–Brazilian armed conflict was an undeclared war.
In a combined offensive against Blanco strongholds, the Brazilian–Colorado troops advanced through Uruguayan territory, taking one town after another. Eventually the Blancos were left isolated in Montevideo, the national capital. Faced with certain defeat, the Blanco government capitulated on 20 February 1865. The short-lived war would have been regarded as an outstanding success for Brazilian and Argentine interests, had Paraguayan intervention in support of the Blancos (with attacks upon Brazilian and Argentine provinces) not led to the long and costly Paraguayan War.
Uruguayan Civil War
Blanco–Colorado strife
The Oriental Republic of Uruguay in South America had been, since its independence in 1828, troubled by strife between the Blanco Party and the Colorado Party. They were not political parties in the modern sense, but factions that engaged in internecine rebellion whenever the other dominated the government. The nation was deeply divided into Colorado and Blanco camps. These partisan groups formed in the 1830s and arose out of patron–client relationships fostered by local caudillos in the cities and countryside. Rather than a unity based upon common nationalistic sentiments, each had differing aims and loyalties informed by their respective, insular political frameworks.
Uruguay had a very low population density and a weak government. Ordinary citizens were compelled by circumstances to seek the protection of local caudillos—landlords who were either Colorados or Blancos and who used their workers, mostly gaucho horsemen, as private armies. The civil wars between the two factions were brutal. Harsh tactics produced ever-increasing alienation between the groups, and included seizure of land, confiscation of livestock and executions. The antagonism caused by atrocities, along with family loyalties and political ties, made reconciliation unthinkable. European immigrants, who came in great numbers during the latter half of the nineteenth century, were drawn into one party or the other; both parties had liberal and conservative wings, so the social and political views of newcomers could be reconciled with either. The feuding blocs impeded development of a broadly supported central national administration.
Liberating Crusade of 1863
In the latter half of the 1850s, leading members of the Colorados and Blancos attempted a reconciliation. With the approval of many from both parties efforts were made to implement "fusionist" policies, which began to show results in cooperation in government and military spheres. The attempt at healing the schism was dealt a setback in 1858 when reactionaries in the Colorado Party rejected the scheme. The revolt was put down by Gabriel Pereira, a former Colorado and Uruguayan president under the fusionist government. The rebellious leaders were executed at Paso de Quinteros along the Río Negro, sparking renewed conflict. The Colorados suspected fusionism of promoting Blanco aims to their own detriment and called for the "martyrs of Quinteros" to be avenged.
With the internal weaknesses of fusionism now exposed, the Colorados moved to oust its supporters from the government. Their leader, Brigadier General Venancio Flores, a caudillo and an early proponent of fusionism, found himself without sufficient military resources to mount a sustained revolt and resorted to asking for intervention by Argentina.
Argentina was a fragmented nation (since the 1852 downfall of Argentine dictator Juan Manuel de Rosas), with the Argentine Confederation and the State of Buenos Aires each vying for supremacy. Flores approached the Buenos Aires Minister of War, Bartolomé Mitre, agreeing to throw the support of the Colorados behind Buenos Aires in exchange for subsequent Argentine assistance in their fight against the fusionist government in Montevideo (the Uruguayan capital). Flores and his Colorado units served Buenos Aires with fierce determination. They played a decisive role in the Battle of Pavón on 17 September 1861, in which the Confederation was defeated and all Argentina was reunited under the government in Buenos Aires.
In fulfillment of his commitment, Mitre arranged for the Colorado militia, Argentine volunteer units and supplies to be carried aboard Argentine vessels to Uruguay in May and June 1863. Ships of the Argentine navy kept Uruguayan gunships away from the operation. Back on his native soil, Flores called for the ouster of the constitutional government, by that time headed by Bernardo Berro. Flores accused the Montevideo government of Blanco sympathies and framed his "Liberating Crusade" (as he called his rebellion) in the familiar terms of a Colorado vs. Blanco struggle. Colorados from rural areas joined defectors from the military in responding to his call.
International crisis
Paraguayan–Blanco ties
Although the Colorados had defected to the Flores insurgency, the national guard continued to support the fusionist government. Blanco partisans filled its depleted ranks. They also replaced army officers who had deserted to Flores. The Blancos received aid from several Argentine Federalists who joined their cause. As in Uruguay, Argentina had long been a battleground of rival parties, and Bartolomé Mitre's victory at Pavón in 1861 had signaled the triumph of his Unitarian Party over the Federal Party led by Justo José de Urquiza. Mitre denied any involvement in the Flores rebellion, even though his complicity was widely known and taken for granted.
Relations between Argentina and Uruguay worsened, and both nations came close to declaring war on each other, although neither could afford a direct military conflict. Argentina had only recently emerged from a long civil war, and was still struggling to suppress a Federalist rebellion in its western province of La Rioja. Uruguay was too weak militarily to engage in a fight unaided.
Since 1862, the Blancos had made repeated overtures to Paraguay, governed by dictator Carlos Antonio López, in an attempt to forge an alliance that might advance both their interests in the Platine region. Upon the death of López, his son, Francisco Solano López, succeeded him as Paraguayan dictator. Unlike the elder López, who strove to avoid encumbering alliances, Solano greeted the Blancos' proposal with enthusiasm. He believed Argentina was working towards the annexation of both Uruguay and Paraguay, with the goal of recreating the Viceroyalty of the Río de la Plata, the former Spanish colony that once encompassed the territories of all three nations. Solano López had, as far back as 1855, expressed this concern, commenting to the Uruguayan Andrés Lamas that "the idea of reconstructing [the old viceroyalty] is in the soul of the Argentines; and as a result, it isn't just Paraguay that needs to stand guard: your country, the Oriental Republic [of Uruguay], needs to get along with my own in order to prepare for any eventualities." In late 1863, Solano López was mobilizing his army and was in talks with Urquiza, the leader of the dissident Argentine Federalists, to convince him to join the proposed Paraguayan–Uruguayan alliance.
Brazil and the civil war
The developments in Uruguay were closely watched by the Empire of Brazil, which had vital interests in the Río de la Plata Basin. After Rosas fell in 1852, Brazil became the dominant regional power. Its foreign policy included the covert underwriting of opposition parties in Uruguay and Argentina, preventing strong governments that might threaten Brazil's strategic position in the area. Brazilian banking and commercial firms also had ventures in the area, furthering ties within the region. In Uruguay, the bank run by Irineu Evangelista de Sousa (Baron and later Viscount of Mauá) became so heavily involved in commercial enterprises that the economy depended on this source of continued capital flow.
About 18 percent (40,000) of the Uruguayan population (220,000) spoke Portuguese and regarded themselves as Brazilian rather than Uruguayan. Many within Flores' ranks were Brazilians, some hailing from the nearby Brazilian province of Rio Grande do Sul. Life along the frontier between Rio Grande do Sul and Uruguay was often chaotic, with hostilities erupting between partisans of various cattle barons, cattle-rustling and random killings. Large landowners on both sides of the border had long been antagonistic toward Berro's policies. The Uruguayan president attempted to tax the cattle coming from Rio Grande do Sul and to impose curbs on the use of Brazilian slaves within Uruguayan territory; slavery had been outlawed years before in Uruguay.
Among the Brazilian land barons were David Canabarro and Antônio de Sousa Neto, both allies of Flores and former separatist rebels during the Ragamuffin War that had ravaged Rio Grande do Sul from 1835 until 1845. Canabarro, a frontier military commander, misled Brazil's government by denying that Brazilians were crossing the border to join Flores. Sousa Neto went to the Brazilian capital to request immediate government intervention in Uruguay, claiming that Brazilians were being murdered and their ranches robbed. The "fact that Uruguayan citizens had just as valid claims against Brazil as Brazilians had against Uruguay was ignored", said historian Philip Raine. Although Sousa Neto had ties with the governing political party, his claims, including that he could amass a force of 40,000 to invade Uruguay, were not taken seriously by all. The Uruguayan crisis arrived at a difficult moment for Brazil, which was on the verge of a full-blown war with the British Empire for unrelated reasons. Brazil's government decided to intervene in Uruguay, fearful of showing any weakness in the face of an impending conflict with Britain, and believing that it would be better for the central government to take the lead rather than allow the Brazilian ranchers on the frontier to decide the course of events.
Early engagements
Brazilian ultimatum
On 1 March 1864, Berro's term of office ended. The ongoing civil war prevented elections; therefore Atanasio Aguirre, president of the Uruguayan senate and a member of the Amapolas (the radical wing of the Blanco Party) replaced Berro, on an interim basis. In April, José Antônio Saraiva was appointed minister plenipotentiary by the Brazilian government and charged with quickly reaching an accord that would settle Brazil's claims and ensure the safety of Brazilian citizens. His focus soon shifted from satisfying Brazil's terms to a more immediate goal of hammering out a deal between the antagonists in the civil war, with the expectation that only a more stable regime would be able to reach a settlement with Brazil.
The government in Montevideo was at first reluctant to consider Saraiva's proposals. With backing from Paraguay, it saw little advantage in negotiating a close to the civil war or in seeking to comply with Brazil's demands. The main factor, as historian Jeffrey D. Needell summarized, was that the "Uruguayan president had been unwilling to resolve these, particularly because the Brazilians whose grievances were at issue were allies of Venancio Flores, a client of the Argentines, and a man who was seeking his overthrow." A mutual enmity between Brazil and its Hispanic-American neighbors compounded the difficulties, the result of a long-standing distrust and rivalry between Spain and Portugal that had been carried over to their former American colonies. Brazil and Uruguay exhibited loathing for one another; as Robert Bontine Cunninghame Graham put it: "the Brazilians holding the Uruguayans as bloodthirsty savages, and the Uruguayans returning their contempt for the unwarlike ways of the Brazilians, whom they called monkeys, and looked down upon, for their mixed blood."
Eventually, in July 1864, Saraiva's persistent diplomacy moved the Uruguayan government to agree to mediated talks including Edward Thornton (the British resident minister in Buenos Aires), Argentine foreign minister Rufino de Elizalde and Saraiva himself. Initially, the negotiations seemed promising, but soon bogged down. On 4 August, convinced that the government in Montevideo was unwilling to work toward a settlement, a frustrated Saraiva delivered an ultimatum, which the Uruguayans rebuffed. On 10 August, Saraiva informed Aguirre that the Brazilian military commanders would receive orders to begin retaliation, marking the beginning of the war.