Together with his colleague, Marcus Valerius Volusus, he fought against the Sabines, whom they defeated decisively near Tibur, obtaining a triumph.
[2] Other authorities state that he fought against the Sabines again, at first with little success, but that he was eventually victorious, and was awarded an ovation, or lesser triumph, which he celebrated on 3 April 503 BC.
[8][9] Additionally, according to Jerome, Postumius and his colleague, Agrippa Menenius Lanatus, held a census during their term of office.
[10][11] In 493 BC, Postumius and Menenius were among the ten ambassadors sent by the senate to treat with the plebs gathered on the Mons Sacer during the first secession.
Led by Menenius, the envoys successfully negotiated an agreement under which the patricians would forgive some of the debt owed by the plebeians; the terms of the agreement also established the office of the tribuni plebis, or "tribunes of the people", who received the power to veto acts of the magistrates and the senate.