Manuel Luís Osório, Marquis of Erval

The allied troops unite under the command of Mitre in the camp of Concordia, in the Argentine province of Entre Ríos, with Field Marshal Manuel Luís Osório at the front of the Brazilian troops.

Some of the troops, commanded by Lieutenant General Manuel Marques de Sousa, baron of Porto Alegre, leave to reinforce Uruguaiana.

Marshal Luís Alves de Lima e Silva, Marquis and, later, Duke of Caxias, assigned on October 10, 1866 to command the Brazilian forces, arrives in Paraguay in November, finding the Brazilian army practically paralyzed.

The contingent of Argentines and Uruguayans, devastated by disease, are cut off from the rest of the allied army.

Mitre and Flores have returned to their respective countries because of difficult internal political conditions.

Tamandaré is replaced in command by Admiral Joaquim José Inácio, future Viscount of Inhaúma.

Osório organizes a five thousand-strong third Corps of the Brazilian army in Rio Grande do Sul.

In Mitre's absence, Caxias assumes general command and restructures the army.