[1]: 91 Taking advantage of the Allies' slow march, he sent colonel Bernardino Caballero with 5,000 men and 12 guns, to stop the enemy at a narrow passage over a stream called Ytororó.

Fernando Machado's brigade, together with Colonel Domingos Rodrigues Seixas's 2nd Infantry Brigade, formed the 2nd Infantry Division, led by Colonel Salustiano Jerônimo dos Reis, a unit which itself pertained to the 2nd Army Corps of Marshal Alexandre Gomes de Argolo Ferrão Filho, responsible for ensuring security when the army disembarked at Guarda de Santo Antonio, more precisely in the rut of the left margin.

[dubious – discuss] The Paraguayan troops were commanded by General Bernardino Caballero, with a force of five to six thousand men, divided into sixteen infantry battalions, six cavalry regiments, and twelve guns.

General Argolo Ferrão told him that it was not possible to attack the enemy position due to the lack of sufficient cavalry and even mules to help pull the artillery.

The path leading to the edge of the stream was tortuous, with a dense vegetation that hindered the movement of the units, and, when Niederauer arrived, the Paraguayans were already entrenched on the other side of the river.

It was already dark and with the rugged and little known terrain, Caxias ordered Niederauer to pull back, but also to tell Argolo about the positions in which the advance forces should remain until dawn.

The first encounter was with Lieutenant Colonel João Antônio de Oliveira Valporto, which progressed with five companies of the 1st Line Battalion toward the Paraguayan artillery.