Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
An incident of more moment was the slaughter of the Epirot garrison by the Locrians, who had formerly surrendered the Roman garrison to the king, and now atoned for one act of treachery by another. By that step the whole south coast came into the hands of the Romans, with the exception of Rhegium and Tarentum. These successes, however, advanced the main object but little.
Lower Italy itself had long been defenceless; but Pyrrhus was not subdued so long as Tarentum remained in his hands and thus rendered it possible for him to renew the war at his pleasure, and the Romans could not think of undertaking the siege of that city. Even apart from the fact that in siege-warfare, which had been revolutionized by Philip of Macedonia and Demetrius Poliorcetes, the Romans were at a very decided disadvantage when matched against an experienced and resolute Greek commandant, a strong fleet was needed for such an enterprise, and, although the Carthaginian treaty promised to the Romans support by sea, the affairs of Carthage herself in Sicily were by no means in such a condition as to enable her to grant that support.
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Reference address : https://www.ellopos.net/elpenor/rome/2-07-pyrrhus-rome-italy.asp?pg=42