During the period of popular discontent in Rome which led to the First secessio plebis, the Volsci, Sabines and the Aequi took up arms against Rome at the same time. To meet the threat and because of the popular political concerns at the time, in 494 BC Valerius was appointed dictator by the Roman senate. He was said to have been chosen because of his moderate temper. His appointment was accepted by the people because of the popularity of his late brother Publius.
Valerius called for conscripts and the people responded positively. Ten legions were raised, a greater number than had been raised previously at any one time. Four of these legions were assigned to the dictator to deal with the Sabines who were regarded as the most serious of the three military threats, and three to each of the consuls to meet the Aequi and the Volsci. Valerius marched with his army to meet the Sabines and won a victory, for which he was awarded a triumph. Additionally the honour of a curule chair in the circus maximus was given to him and his descendants.
After the armies' return to Rome, Valerius requested the senate to deal with the ongoing debt issues which were afflicting the people. The senate declined to act, and the dictator was outraged. He said before the senate: He resigned his commission, and went to his house, greeted by the applause of the people. In some traditions, following his dictatorship, he was first elected augur in 494 BC and then princeps senatus during the census of 493 BC. He would remain an augur until his death in a pestilence in 463 BC.
Legacy
In AD 2, a statue of Marcus Valerius Maximus was erected in the Forum of Augustus alongside other "great men of Rome", under which was an elogia.
Conflicting identification and death
Festus identifies Manius Valerius Maximus as a son of Marcus Valerius Volusus and puts him as Romes first dictator in 501 BC. Similarly there some confusion in regards to the Valerius who is chosen as Augur in 494 BC, which can be either identified as the former consul Marcus Valerius Volusus, his son, the previously mentioned Manius Valerius Maximus, or this Manius Valerius Maximus, the dictator of 494 BC. If it was either of the brothers to Poplicola they would have been extremely old by 463 BC when this Augur is said to have succumbed during a large pestilence in Rome.