5. M.AtiliusRegulus, M. F. M. N., son of the Regulus who perished in Africa [No. 3], was consul for the first time in B. C. 227, with P. Valerius Flaccus, in which year no event of importance is recorded (Fasti; Gel. 4.3). He was elected consul a second time in B. C. 217, to supply the place of C. Flaminius, who had fallen in the battle of the Trasimene lake. He carried on the war against Hannibal together with his colleague Servilius Geminus, on the principles of the dictator Fabius. At the end of their year of office their imperium was prolonged, as the new consuls had not yet been elected; but when Aemilius Paulus and Terentius Varro were at length appointed, and took the field, Regulus was allowed to return to Rome on account of his age, and his colleague Servilius remained with the army (Liv. 22.25, 32, 34, 40). Polybius, on the contrary, says (3.114, 116) that Regulus remained with the new consuls, and fell at the battle of Cannae, where he commanded, with Servilius, the centre of the line. This statement, however, is erroneous, and we must for once follow Livy in preference to Polybius, since it is certain that the same Regulus was censor two years after the battle of Cannae. (Comp. Perizonius, Anim>adv. Hist. 100.1, sub fin.; and Schweighäuser, ad Polyb. 3.114.)

After the battle of Cannae, B. C. 216, Regulus was one of the triumviri mensarii, who were appointed on account of the scarcity of money. In B. C. 214 he was censor with P. Furius Philus. These censors punished with severity all persons who had failed in their duty to the state during the great calamities which Rome had lately experienced. All those who had formed the project of leaving Italy after the battle of Cannae, and all those who had been taken prisoners by Hannibal, and when sent as ambassadors to Rome on the promise of returning to the Carthaginian camp, had not redeemed their word, were reduced to the condition of aerarians. The same punishment was inflicted on all the citizens who had neglected to serve in the army for four years without having a valid ground of excuse. Towards the end of the year, when the new tribunes of the people entered upon their duties, one of their number, Metellus, who had been reduced to the condition of an aerarian by the censors, attempted to bring these magistrates to trial before the people, but was prevented by the other tribunes from prosecuting such an unprecedented course [METELLUS, No. 2]. As Furius Philus died at the beginning of the following year, before the solemn purification (lustrum) of the people had been performed, Regulus, as was usual in such cases, resigned his office. (Liv. 23.21, 24.11, 18, 43; V. Max. 2.9.8.)