[2] He was then to Paraguay in the first half of 1865 as the commander of the 1st Battalion of Volunteers for the Homeland, as he was informed of the invasion of Rio Grande do Sul[2] near São Borja.

The Paraguayans' decision to only take São Borja after crossing the river with only five thousand men and was caused by the impression that the soldiers were a vanguard of the Imperial Brazilian Army.

Colonel João Manuel took advantage of this to effect, at night, the strategic withdrawal of all the families from São Borja and was praised for this.

[2] In November and December of the same year he excelled in combat, later fighting in battles of Avay and Lomas Valentinas.

[2][3] His death infuriated the Brazilian commander Count of Eu, who ordered the beheading of Colonel Pablo Caballero and the political chief of the village, Patrício Marecos.