Battle of Lake Regillus The Battle of Lake Regillus was a legendary Roman victory over the Latin League shortly after the establishment of the Roman Republic . The Latins were led by an elderly Lucius Tarquinius Superbus , the seventh and last King of Rome , who had been expelled in 509 BC , and his son - in - law , Octavius Mamilius , the dictator of Tusculum . The battle marked the final attempt of the Tarquins to reclaim their throne . According to legend , Castor and Pollux fought on the side of the Romans . Background . The threat of invasion by Rome ' s former allies in Latium led to the appointment of Aulus Postumius Albus as dictator . The year in which the battle occurred is unclear , and has been since ancient times . Livy places the battle in 499 BC , but says some of his sources also suggest the battle occurred during Postumius ' consulship in 496 . The other major source for this historical period , Dionysius of Halicarnassus also places the battle in 496 . Modern authors have suggested 498 BC or 493 BC . Lake Regillus was located in the relic of a volcanic crater between Rome and Tusculum . The lake was drained in the fourth century BC . According to Livy , the Volsci ( a neighbouring tribe to the south of Latium ) had raised troops to send to the aid of the Latins against Rome , however the haste of the Roman dictator in joining battle meant that the Volscian forces did not arrive in time . Battle . The dictator Postumius led the Roman infantry , while Titus Aebutius Elva was Master of the Horse . Tarquin was accompanied by his eldest and last remaining son , Titus . It was said that the presence of the Tarquinii caused the Romans to fight more passionately than in any previous battle . Early in the battle , the king was injured attacking Postumius . The magister equitum charged at Mamilius , and both were wounded , Aebutius in the arm , and the Latin dictator in the chest . The magister equitum had to withdraw from the field , and direct his troops from a distance . The king ' s soldiers , including many exiled Romans , began to overpower the republican forces , and the Romans suffered a setback when Marcus Valerius Volusus ( consul in 505 BC ) was killed by a spear while attacking Titus Tarquinius , but Postumius brought fresh troops from his own bodyguard , and halted the exiles ' progress . Meanwhile , Titus Herminius Aquilinus , who had won fame fighting alongside Horatius at the Sublician bridge , and served as consul in 506 BC , engaged Mamilius , and slew him ; but while attempting to strip his fallen enemy and claim the spoils , Herminius was killed by a javelin . As the outcome of the battle seemed in doubt , Postumius ordered the equites to dismount and attack on foot , forcing the Latins to retreat and capturing the Latin camp . Tarquin and the Latin army abandoned the field , and the result was a decisive Roman victory . Postumius and his army returned to Rome , where the dictator celebrated a triumph . A popular legend reported that the Dioscuri , Castor and Pollux , fought alongside the Romans , transfigured as two young horsemen . Postumius ordered a temple built in their honour in the Roman Forum , in the place where they had watered their horses . In the nineteenth century , the battle was celebrated in Thomas Macaulay ' s " Lays of Ancient Rome " . < / div > < / div >