He was censor in 332 BC and magister equitum in 327 BC, when Marcus Claudius Marcellus was appointed to hold the comitia. In 321 BC, he was consul a second time with Titus Veturius Calvinus, and with him marched against the Samnites and their commander Gaius Pontius in the Second Samnite War. Postumius was defeated at the Battle of the Caudine Forks, near Caudium, and obliged to surrender with his whole army, who were sent "under the yoke", a symbolic gesture of submission to the enemy.