When the Roman praetor had satisfied himself that after so many days' inaction the enemy would not expect him to take the initiative, he ordered L. Acilius to take the division of allied troops and 6000 native auxiliaries, and make a circuit round the mountain which lay behind the enemy's camp. When he heard the battle-shout he was to charge down on their camp. They started in the night to escape observation. At daybreak Flaccus sent C. Scribonius, the commander of the allied troops, with his "select" cavalry up to the enemy's rampart. When the Celtiberi saw them approaching more closely and in greater strength than they had usually done, the whole of their cavalry streamed out from the camp and the signal was given for the infantry also to advance. Scribonius, acting on his instructions, no sooner heard the clatter of the advancing cavalry than he turned his horses' heads and made for his camp. The enemy followed in hot haste. First their cavalry came up and soon after the infantry, never doubting but that they would that day capture the Roman camp. They were not now more than half a mile from the rampart. As soon as Flaccus considered that they were sufficiently drawn off from guarding their own camp he sallied forth from his camp, his army which had previously been drawn up inside the rampart being formed into three separate corps. The battle-shout was raised not only to stimulate the ardour of the combatants but also to reach the ears of those who were amongst the hills. Without a moment's delay these charged down, as they had been ordered, on the enemy's camp, where not more than 5000 men were left on guard. The strength of the assailants compared with their own scanty numbers and the suddenness of the attack so appalled them that the camp was taken with little or no resistance. When it was captured Acilius set fire to that part of it which could be best seen from the field of battle.