Mato Grosso Campaign

Paraguay took the initiative during the first phase of the war: invading Mato Grosso in the north on 14 December 1864,[1]^:25 Rio Grande do Sul in the south in early 1865, and the Argentine province of Corrientes.

Vicente Barrios.

Two separate Paraguayan forces invaded Mato Grosso simultaneously. An expedition of 3,248 troops, commanded by Col. Vicente Barrios, was transported by a naval squadron under the command of Capitan de Fragata Pedro Ignacio Meza, up the Río Paraguay to the town of Concepcion.[1]^:25 They attacked the Nova Coimbra fort on 27 Dec.[1]^:26 The Brazilian garrison of 154 men resisted for three days, under the command of Lt. Col. Hermenegildo de Albuquerque Porto Carrero (later Baron of Fort Coimbra). When their munitions were exhausted, the defenders abandoned the fort and withdrew up the river towards Corumbá on board the gunship Anhambaí.[1]^:26 After occupying the fort, the Paraguayans advanced north, taking the cities of Albuquerque, Tage, and Corumbá in January 1865.[1]^:26 He then sent a detachment to attack the military frontier post of Dourados. This detachment, led by Maj. Martín Urbieta, encountered tough resistance on 29 December 1864, from Lt. Antonio João Ribeiro and his 16 men, who were all eventually killed. The Paraguayans continued to Nioaque and Miranda, defeating the troops of Col. José Dias da Silva. Coxim was taken in April 1865. The second Paraguayan column, formed from some of the 4,650 men led by Col. Francisco Isidoro Resquín at Concepcion, penetrated into Mato Grosso with 1500 troops.[1]^:26

Despite these victories, the Paraguayan forces did not continue to Cuiabá, the capital of the province, where Augusto Leverger had fortified the camp of Melgaço to protect Cuiabá. Their main objective was the capture of the gold and diamond mines, disrupting the flow into Brazil until 1869.[1]^:27

Brazilian expedition to Mato Grosso: Encampment of the Expeditionary Division in the virgin forests of Goiás.

Brazil sent an expedition to fight the invaders in Mato Grosso. A column of 2,780 men led by Colonel Manuel Pedro Drago left Uberaba in Minas Gerais in April 1865, and crossed the Apa River into Paraguay in April 1867. In January 1867, Colonel Carlos de Morais Camisão had assumed command of the column after the deaths of Drago and Galvao. The column by April numbered 1,907 men.[1]^:69

President Lopez sent the 21st Cavalry Regiment to Concepcion to reinforce the cavalry under Maj. Martin Urbieta. Though winning the Battle of Baiende, Col. Camisão was forced to retreat due to lack of supplies, which further reduced his force to 578 men. [1]^:69 Though he died of cholera along the way, the remaints of his force reached Canuto on 11 June.[1]^:70