He served as one of the main Paraguayan commanders during the Invasion of Rio Grande do Sul, organizing the Battle of São Borja and the Siege of Uruguaiana before his surrender.

[4]Nor did Solano López send the requested reinforcements and the allied army finally defeated Duarte's division at the Battle of Yatay with which Estigarribia was isolated.

But at the beginning of September the situation became desperate due to the lack of food and when the commander of the Paraguayan division of the allied army wrote to him rejecting the charge of treason and accusing López of betraying his homeland for carrying out a policy.

On September 18, while the allied army was taking positions for an assault, Marques de Souza sent it a final summons that was accepted by Estigarribia with no further condition that the superior commanders could return to Paraguay or withdraw wherever they wished and that the Uruguayan soldiers and officers that formed in their ranks were not handed over to Flores.

While many imprisoned Paraguayan soldiers were turned into slaves in Brazil[8] or incorporated into the allied armies,[9] Estigarribia remained in Rio de Janeiro for the rest of his days alive.