The date of the battle has been traditionally given as 390 BC in the Varronian chronology, based on an account of the battle by the Roman historian Livy. Plutarch noted that it took place "just after the summer solstice when the moon was near the full [...] a little more than three hundred and sixty years from the founding Rome," or shortly after 393 BC. The Greek historian Polybius used a Greek dating system to derive the year as 387 BC, which is the most probable. Tacitus listed the date as 18 July.