The defeat of the Vocates and Tarusates (56 B.C.) was the second of two major battles in unknown locations in which Publius Crassus, the son of the Triumvir and one of Caesar's most able lieutenants, defeated the Aquitani tribes of south-west Gaul.
Crassus had been sent into Aquitaine on rather spurious grounds – to make sure that they didn’t send any auxiliaries to aid the rebellious Veneti on the north-west coast of Gaul. Caesar had given Crassus twelve cohorts of infantry and a large force of cavalry, which Crassus had reinforced with auxiliaries and extra cavalry from the Roman Province in southern Gaul. He had then advanced into the territory of the Sotiates, defeating them in battle and then forcing them to surrender by besieging their chief towns.
Crassus's next targets were the Vocates and Tarusates tribes. They proved to be a rather more difficult opponent. The campaign against the Sotiates had given them time to raise troops from northern Spain. Many of these men had fought with Q. Sertorius, a rebellious governor of Spain who had defied the Republic for a decade (Sertorian War), and they had learnt a great deal from that experience.
Crassus was soon badly outnumbered. According to Caesar the Vocates, Tarusates and their allies had 50,000 men, while Crassus had slightly more than one legion of infantry and his auxiliaries – at least 5,000 men.
Crassus soon found himself in a rather dangerous position. The Aquitani and their allies built a well positioned and apparently strongly fortified camp, and then concentrated on preventing any supplies from reaching the Romans. The Romans were too badly outnumbered to be able send detachments out to gather supplies, and so Crassus decided that his best chance of success was to fight a battle.
On the day after this decision was made the Romans came out of their camp and formed up in a double line. Crassus was hoping that the Aquitani would accept this challenge to fight, but instead they decided to wait the Romans out, remain in their camp and wait for a lack of supplies to force Crassus to retreat.
Young Crassus, who appears to have been a typical cavalry general, decided to force the issue by storming the enemy camp. Eight of his twelve infantry cohorts attacked the front of the camp, four remained to guard the Roman camp, and cavalry was sent to ride around the enemy camp to scout it out.
Caesar gives details of the nature of the attack on the Aquitanian camp. Crassus didn't trust his auxiliaries to fight, so they were used to carry rocks and extra weapons to the legionaries. They were split into two bodies – one half used darts to force the defenders off their ramparts, while the other half filled the ditch. The dart throwing troops were not entirely effectively, and the defender's own missile fire was described as 'not ineffectual'.
At some point during this frontal assault Crassus's cavalry returned from their ride around the enemy camp and reported at the rear gate was not well fortified. Crassus sent the four cohorts that had been guarding the camp on a wide flanking march. Not only were the rear fortifications weak, they were also unguarded, and the four cohorts were able to break into the enemy camp before they were discovered. The noise from within the camp encouraged the eight cohorts at the front to renew their attack.
The Aquitania were now trapped between two Roman forces. Some of them attempted to escape over their own ramparts, but were pursued by the Roman cavalry. Caesar claimed that only a quarter of 50,000 men escaped (not that they were the only survivors). In the aftermath of this defeat most of the Aquitanian tribes surrendered to Crassus and sent hostages to ensure their good behaviour.