On 15 November 1853 he was appointed Chief of Staff of the Superior Command of the National Guard of Brazil, being promoted to brigadier on 2 December 1856 .

[2] With the outbreak of the Paraguayan War, general Manuel Luís Osório, then Commander-in-Chief of the Brazilian Army in Paraguay, requested the appointment of a trusted officer who could replace him in the event of impediments.

Polidoro was then appointed by the imperial government, not only for Osório's impediments, but also to replace the Viscount of Porto Alegre in command of the 2nd Army Corps.

As soon as he arrived in Paraguay, with Osório's ailments increasing, Polidoro took command of the 1st Army Corps, beginning his work in the Battle of Curupayty, in which the Allied forces suffered a great defeat.

[4] Polidoro died in Rio de Janeiro on 13 January 1879 with the rank of lieutenant general; his remains were buried in the São João Batista Cemetery.