Fifteen Roman cohorts were wiped out at Atuatuca Tungrorum (modern Tongeren in Belgium) and a garrison commanded by Quintus Tullius Cicero narrowly survived after being relieved by Caesar in the nick of time.

To the Eburones he sent Quintus Titurius Sabinus and Lucius Aurunculeius Cotta with the command of a recently levied 14th Legion from north of the Po and a detachment of five cohorts, a total strength of 9,000 men.

He pointed out that experience had shown them that Germans could be resisted from behind their fortifications, that they had plenty of supplies, were within easy reach of assistance from nearby legions and that they should take at face value neither the news nor the advice of an enemy.

Denying that he was motivated by fear, Quintus Titurius Sabinus said that he believed that Caesar was on his way to Italy, that the Germans were about to add to the number of the besieging Eburones and that it seemed that they were about to face the combined wrath of grudge-ridden Germans and Gauls—for surely the militarily weak Eburones would not dare to face a Roman legion otherwise.

When dawn broke, the Romans, in marching order (long columns of soldiers with each unit following the other), more heavily burdened than usual left the Fort.

Due to the length of the column, the commanders could not issue orders efficiently so they passed word along the line to the units to form into a square.

However, Ambiorix, after promising Sabinus his life and the safety of his troops, distracted him with a long speech, all the while slowly surrounding him and his men and slaughtering them.

The Gauls then charged down en masse onto the waiting Romans where they killed Cotta, still fighting, and the great majority of the troops.

Titus Labienus, the commander of the Fourth legion, which was stationed in the southern Ardennes, discovered that Indutiomarus and the Treveri were rebelling as well.

Before targeting the Eburones themselves, Caesar first attacked Ambiorix's allies, forcing them to promise that they would not help the tribe who had destroyed Cotta and Sabinus.

Five legions were sent because, according to Caesar, they, alone of all the tribes of Gaul, had never sent ambassadors to him to discuss terms of peace, and had ties of hospitality with Ambiorix.

[3] After this Caesar built a bridge across the Rhine and campaigned in Germania to punish the German tribes who had aided the Treveri.