Corrientes campaign

The Corrientes campaign or the Paraguayan invasion of Corrientes was the second campaign of the Paraguayan War. Paraguayan forces occupied the Argentinian city of Corrientes and other towns in Corrientes Province. The campaign occurred at the same time as the Siege of Uruguaiana.
Argentina and Uruguay declared war against the Paraguayan invaders, who were already at war with the Empire of Brazil, and signed the Treaty of the Triple Alliance. The Paraguayan invasion of Argentina failed, but led to the invasion of Paraguay in later campaigns.

Background

Military situation

In the early 1860s, liberal parties took power during civil wars in Argentina and Uruguay. In Argentina, General Bartolomé Mitre assumed the presidency in 1862. Mitre and Uruguayan General Venacio Flores were allied with the Empire of Brazil, and Flores launched a rebellion to take power with Brazilian and Argentinian support.
Faced with the advance of liberal forces backed by the empire, the conservative Paraguayan government of Marshal Francisco Solano López anticipated that Brazil and Argentina would try to incite a civil war in Paraguay. Solano Lopez, on the other hand, wanted to influence the other countries in the Río de la Plata basin.
The Brazilian- and Argentinian-backed invasion of Uruguay by Flores motivated López to demand the withdrawal of foreign forces from Uruguay at the Uruguayan government's request.
The Paraguayan invasion of Mato Grosso was a success, but the Partido Blanco government in Uruguay was defeated and General Flores assumed the presidency.
López asked Argentinian president Bartolomé Mitre to allow his troops to cross Corrientes Province towards the Uruguay River to restart the civil war in Uruguay and attack the Brazilian province of Rio Grande do Sul. López told Mitre that Argentina was neutral in the conflict between Paraguay and Brazil and, since he had allowed Uruguayan rebel troops and the Brazilian navy to cross Argentine territory and jurisdictional waters, López could expect the same authorization for Paraguayan troops going to Brazil or Uruguay. Mitre refused, saying that he could not allow the passage of troops through his territory and remain neutral.

Plans

Paraguay invaded and occupied Mato Grosso, although Brazil had claimed some of that territory. Paraguay had little or no communication with the rest of Brazil, so Paraguayan troops could not further advance into Brazil to force it to surrender or negotiate. For results in Uruguay or to prevent further attacks on Paraguayan territory, it had to continue the war in the province of Rio Grande do Sul.
Before Mitre's refusal, López had planned to concentrate his forces along the Uruguay River to attack Brazil or enter Uruguayan territory. When war was declared on Argentina, however, he needed to prevent the Argentine Army from hindering the Paraguayan advance with a diversionary maneuver along the Uruguay River. The objective was to occupy the city of Corrientes, a strategy that would also make it possible to control the upper Paraná River, leaving communications open through Corrientes Province.
Between the decision to invade and the troop advance, López decided to use troops occupying the capital of the invaded province to support the passage on the Uruguay River. Instead of concentrating most of the troops in this last column, he formed an army of only about 12,000 men and sent 25,000 soldiers to the Paraná River.
Before implementing his plan, López sent Lieutenant Cipriano Ayala to deliver the declaration of war to Buenos Aires. War was declared on 18 March 1865, and was published in Asunción a week later. The attack would be launched after the expected delivery date of the declaration of war but before the news arrived back in Paraguayan territory to give the disorganized, under-equipped Argentine army no time to react. The messenger carrying the declaration of war met with many obstacles, however, and the Argentine public learned about the invasion of Corrientes before it heard about the declaration of war.

Occupation of Corrientes

At dawn on 13 April 1865, a squadron of five Paraguayan steamboats appeared at the city of Corrientes with a landing party of 2,500 under the command of Commander Pedro Ignacio Meza. They passed the city headed south, then turned north and attacked the Gualeguay and the 25 de Mayo ; the 25 de Mayo had a crew of 80 men. The crews of two Paraguayan ships boarded the Argentine ships, and captured them after a skirmish with some casualties. About 3,500 to 4,000 men landed and occupied the city the following day.
After the attack, residents led by constructed a defense on the roofs of houses closest to the port. The attacking fleet withdrew, and an attempt was made to organize battalions under Colonel Solano González; volunteers were summoned to the Plaza 25 de Mayo and the Plaza del Mercado.
Paraguayan general Wenceslao Robles had settled in Paso de Patria with more than three thousand men, awaiting the Paraguayan fleet after it attacked Corrientes. Robles loaded as many soldiers as he could; the small Paraguayan squadron returned to Corrientes at dawn on 14 April, taking possession of the city square without any resistance. Shortly afterward, the column from Paso de la Patria arrived under Robles and the rest of the invading forces. The 25 de Mayo and Gualeguay did not return to Corrientes, since they had been incorporated into the Paraguayan Navy and sent to Asunción for repairs.
The Argentine authorities withdrew with the few battalions, which could not resist the invading Paraguayan forces. Withdrawing to the interior was their only option to reorganize under Nicanor Cáceres, who harassed the invaders and kept the troops loyal to Governor Manuel Lagraña.
Corrientes reacted in two different ways. Some residents fled to rural areas away from the city, to country houses in Lomas; others crossed the Paraná and took refuge in the interior of the Chaco Territory. The rest, a significant fraction of the population, did not resist the Paraguayan troops. A contemporary chronicler wrote that the city's inhabitants were not hostile to the invaders, which made it easier for them to receive good treatment.
Paraguayan control of the square was irreversible in principle, so Governor Lagraña, his closest collaborators, and security groups moved to rural areas to avoid being taken prisoner. Before he withdrew, Lagraña ruled that every citizen of Corrientes between sixteen and seventy years of age was required to enlist and fight the occupation forces.
In the afternoon, a column of 800 cavalry arrived by land and entered the city. Robles met with a popular assembly apparently consisting of members of the Federalist Party and other opponents of the national government. A provisional government was formed by Teodoro Gauna, and Sinforoso Cáceres. Local political action was carried out by Cáceres, but the triumvirate was limited to endorsing the activities of the Paraguayan commissioners José Berges, Miguel Haedo and Juan Bautista Urdapilleta in commercial matters and relations with Paraguay.
The Federalist Party leaders in the capital initially supported the Paraguayan occupation as allies in their attempt to recover the political dominance they had lost at the end of 1861 after the Battle of Pavón and the Corrientes revolution. Colonel Cayetano Virasoro stood out, although he was later accused of collaborating with the Paraguayans. The Paraguayan troops continued to receive reinforcements, reaching just over 25,000 men over the following days.
Lagraña assembled the province's population and summoned all males between 17 and 50 years of age to arms. He entrusted Colonel Desiderio Sosa with the military organization of the capital and its surroundings, and settled in the nearby town of San Roque. Lagraña gathered about 3,500 volunteers, many of whom had no military experience and very little equipment. He was joined a few weeks later by General Nicanor Cáceres, who arrived from the Curuzú Cuatiá area and contributed about 1,500 men.
The presence on the governor's side of Cáceres, who was considered to belong to the Federalist Party, cooled federal enthusiasm for the invaders and deprived them of provincial support. As the Paraguayan army began its advance south, Lagraña and his army had to withdraw to Goya.
In the early hours of 11 July 1865, Paraguayan soldiers kidnapped Toribia de los Santos, Jacoba Plaza, Plaza's son Manuel, Encarnación Atienza, Carmen Ferré Atienza and her daughter Carmen, Victoria Bar and wives of the Corrientes resistance leaders from their homes. The occupation of Corrientes was difficult for its inhabitants. In his essay La toma de Corrientes, Wenceslao Domínguez wrote:
In his book Historia ilustrada de la provincia de Corrientes, historian Antonio Emilio Castello wrote:

Argentine reaction

The population of the big cities denounced the invasion, which they saw as unjustified and treacherous. President Mitre's speech, delivered the day that news of the attack arrived in Buenos Aires, included the later-reviled phrase "In 24 hours to the barracks, in fifteen days in Corrientes, in three months in Asunción!" and fueled the desire for revenge. Many young men rushed to enlist in regiments created for the war. The same thing happened in Rosario, and to a lesser extent in Córdoba and Santa Fe. The reaction in the rest of the country was very different; only the most determined supporters of the ruling party publicly opposed the Paraguayan attack.
Entre Ríos Province opposed the national government. Respecting his previous commitments, governor and former president Justo José de Urquiza assembled a provincial army of 8,000 men and moved it to the northern border of the province. When they reached Corrientes in July 1865, soldiers who had believed that they were going to fight on the Paraguayan side rose up in the and deserted en masse. The central government refrained from reprisals against the rebels. Urquiza recruited about 6,000 soldiers from the provincial forces who had a reputation as excellent cavalry troops, but they disbanded in the in November 1865. This second rebellion was harshly repressed with the help of Brazilian and Uruguayan troops.
On 1 May, the Treaty of the Triple Alliance was signed by Argentina, Uruguay, and Brazil. The speed with which an agreement was reached makes a number of historians suspect that the treaty had been prepared in advance.
Mitre gathered the available troops in Buenos Aires, Rosario, and San Nicolás de los Arroyos, and moved a strong division north aboard the war fleet. He ordered each provincial government to provide a large contingent of infantry forces to reinforce the enlisted troops. Most of the cavalry who served in the frontier forts with indigenous people in the south of the country were also sent north.