Invasion of Rio Grande do Sul

The Corrientes campaign began when the Paraguayans invaded Argentina in April 1865 after the Argentines denied the passage of López's troops over their territory. About 30,000 Paraguayan soldiers invaded and occupied the Corrientes Province.

In order to force a favorable peace agreement with the Brazilians, López ordered the invasion of Rio Grande do Sul. Under the command of Antonio Estigarribia, from 10 to 12,000 soldiers were mobilized for the invasion and divided into 2 columns. The main one, with 7,500 men under the direct command of Estigarribia himself, had the mission of entering Brazilian territory. 3,000 men led by major Pedro Duarte didn't cross the Uruguay River and accompany the first column on the river's coast.^[1] On the morning of June 10, 1865, Estigarribia began preparations for the crossing. The Paraguayans crossed the river by canoe and on foot and with them 5 cannons and 30 carts with supplies. At 10 am, the Paraguayans began the Battle of São Borja, encountering weak resistance from lancers commanded by colonel Ferreira Guimarães. The battle lasted 2 days when the Brazilians finally withdrew from the village, which was then occupied and looted by the invaders for a week. Encouraged by the victory, the Paraguayans marched south, always on the banks of the Uruguay River.^[2]

On June 26, a contingent of about 500 men encountered a Brazilian column of 2,000 soldiers of colonel Antônio Fernandes Lima near the Butuí stream, suffering a defeat and the remainder fled to the main column of Estigarribia,^[3] being the only successful Brazilian opposition before Uruguaiana.^[4][5] When the Paraguayans arrived in Itaqui on July 7, they found it almost empty, without resistance, where they looted and stayed for eight days, waiting for further instructions.

Disobeying orders from Francisco Solano López to remain in Ybicuí, about 36 kilometers from Itaqui, colonel Estigarribia ordered his troops to march south towards Uruguaiana.^[6] The advance was difficult for the Paraguayans as it was a rainy and particularly cold period and the troops did not have tents, proper uniforms or footwear. Estigarribia knew the extreme danger of crossing the Ibicuí River as it was full of currents, the potential loss of the supply carts, cannons and luggage and the possibility of an ambush by colonel Fernandes Lima. Despite this, the troops crossed the river, being harassed by a few hundred Brazilian soldiers who preferred not to engage in combat. The Paraguayan commander was astonished at the ease of crossing the Ibicuí which, according to him, was due to the refusal of the Brazilians, commanded by David Canabarro, to "dispute us over the passage of this river, which presented immense advantages to the enemy". He wrote to the López that he hoped to be able to communicate "within a few days" that the village of Uruguaiana was in Paraguayan hands.^[7]

On August 2, major Duarte occupied Paso de los Libres, and three days later Estigarribia with his 7,000 men occupied Uruguaiana, across the river, in Brazilian territory. Estigarribia had orders to continue eastward, approaching Alegrete, but stopped to wait for troops to come from Paraná. When he learned that these forces would not come to his aid, Estigarribia repeatedly asked him to send aid from Paraná. López never responded to the request.^[8] Soon around 17,000 soldiers from the newly formed Triple Alliance under the leadership of the Count of Porto Alegre began the siege in August 1865. After several stages from the allies, the last being on September 18, with the threat of invasion of the city, in addition to hunger and lack of help from López, Estigarribia surrendered with about 6,000 of his men, thus ending the campaign in Rio Grande do Sul.

• Borga, Ricardo Nunes (2015). Clube de Autores (ed.). Questões do Prata - Guerra da Tríplice Aliança, O conflito que mudou a América do Sul (2 ed.). Rio de Janeiro.{{cite book}}: CS1 maint: location missing publisher (link)
• Cardozo, Efraim (1968). EMASA (ed.). Hace 100 años: cronicas de la guerra de 1865-1870. Publicadas en "La Tribuna" de Ascunicón en el Centenario de la Epopeya Nacional. Maps de Roberto Thompson. Vol. 2 (2 ed.). Asunción.{{cite book}}: CS1 maint: location missing publisher (link)
• Estigarribia, Antonio de la Cruz (1965). Revista Militar Brasileira (ed.). Ocupação de Uruguaiana: diário militar (4 ed.).
• Gay, Eduardo Pedro (1980). IEL/EST/UCS (ed.). A invasão paraguaia na fronteira brasileira do Uruguai, pelo cônego (5 ed.). Porto Alegre.{{cite book}}: CS1 maint: location missing publisher (link)
• Lima, Luiz Octávio de (2016). Planeta do Brasil (ed.). A Guerra do Paraguai. São Paulo. p. 389. ISBN 9788542207996. OCLC 972903102.{{cite book}}: CS1 maint: location missing publisher (link)
• Rosa, José María (1986). Hyspanamérica (ed.). La guerra del Paraguay y las montoneras argentinas. A. Peña Lillo. ISBN 950-614-362-5.
• Silva Pinto, Luís Flodoardo (2002). AGE Editora (ed.). A Batalha de Uruguaiana : episódio da Guerra da Tríplice Aliança (1864-1870). Porto Alegre. ISBN 8574971324.{{cite book}}: CS1 maint: location missing publisher (link)