The left, which was in a much closer formation, was further strengthened by a rapid manoeuvre of Poetilius, who suddenly brought up into the fighting line the cohorts which were usually kept in reserve, in case the battle was prolonged. He then charged the enemy with his full strength.

As the Samnite infantry were shaken by the weight of the attack their cavalry came to their support, and riding obliquely between the two armies were met by the Roman cavalry who charged them at a hard gallop and threw infantry and cavalry alike into confusion, until they had forced back the whole line in this part of the field.