From them he learned that the Belgae could muster about 300,000 men.
By skilful tactics and a successful attack he put to flight and nearly annihilated the Suessiones.

The Bellovaci now put themselves under his protection, but the Nervii remained in arms.

One day, while the six legions were forming camp on the bank of the river Sabis, the Nervii and their allies suddenly rushed upon them from an ambuscade in the woods on the opposite bank.

The troops were entirely unprepared, and so quick was the enemy's charge that the Romans had not time to put on their helmets, to remove the covering from their shields, or to find their proper places in the ranks.

Great confusion followed, and they became almost panic-stricken.