Aemilius, who had heard of the landing of the legions at <a class="linkToPlace" target="_blank" href="/place?placename=Pisa&groupId=904&placeId=1625">Pisa</a> but had not any idea that they were already so near him, now, when he saw the fight going on round the hill, knew that the other Roman army was quite close.
Accordingly, sending on his cavalry to help those who were fighting on the hill, he drew up his infantry in the usual order and advanced against the foe.
The Celts had drawn up facing their rear, from which they expected Aemilius to attack, the Gaesatae from the <a class="linkToPlace" target="_blank" href="/place?placename=Alps&groupId=313&placeId=609">Alps</a> and behind them the Insubres,
and facing in the opposite direction, ready to meet the attack of Gaius' legions, they placed the Taurisci and the Boii from the right bank of the Po.
Their wagons and chariots they stationed at the extremity of either wing and collected their booty on one of the neighbouring hills with a protecting force round it.
This order of the Celtic forces, facing both ways, not only presented a formidable appearance, but was well adapted to the exigencies of the situation.
The Insubres and Boii wore their trousers and light cloaks,
but the Gaesatae had discarded these garments owing to their proud confidence in themselves, and stood naked, with nothing but their arms, in front of the whole army, thinking that thus they would be more efficient, as some of the ground was overgrown with brambles which would catch in their clothes and impede the use of their weapons.
At first the battle was confined to the hill, all the armies gazing on it, so great were the numbers of cavalry from each host combating there pell-mell.
In this action Gaius the Consul fell in the mellay fighting with desperate courage, and his head was brought to the Celtic kings; but the Roman cavalry, after a stubborn struggle, at length overmastered the enemy and gained possession of the hill.
The infantry were now close upon each other, and the spectacle was a strange and marvellous one, not only to those actually present at the battle, but to all who could afterwards picture it to themselves from the reports.
Walbank Commentary