Julius Civilis had a personal reason for this policy. Claudius Labeo, the former commander of the Batavian cavalry unit that had decided a battle in favor of Julius Civilis but had been rewarded with an exile in Frisia, had made his escape. He had been able to reach general Caius Dillius Vocula, who had helped him to form a small army that attacked the Batavian and Cananefatian homelands from the south. Civilis hated Labeo, and knew that the Batavians at home wanted an end to this guerilla war. The two armies met near the bridge of Trajectum Mosae, Maastricht.
Civilis found his advance blocked by the resistance of Claudius Labeo and his irregular body of Baetasii, Tungrians and Nervians. Labeo relied on his position astride a bridge over the river Maas which he had seized in the nick of time. The battle fought in this confined space gave neither side the advantage until the Batavians swam the river and took Labeo in the rear. At the same moment, greatly daring or by prior arrangement, Civilis rode up to the Tungrian lines and exclaimed loudly: 'We have not declared war to allow the Batavians and Trevirans to lord it over their fellow-tribes. We have no such pretensions. Let us be allies. I am coming over to your side, whether you want me as leader or follower.' This made a great impression on the ordinary soldiers and they were in the act of sheathing their swords when two of the Tungrian nobles, Campanus and Juvenalis, offered him the surrender of the tribe as a whole. Labeo got away before he could be rounded up. Civilis took the Baetasii and Nervians into his service too and added them to his own forces. He was now in a strong position, as the communities were demoralized, or else felt tempted to take his side of their own free will.
,br> The Latin words that have been translated here as 'in this confined space' (in angustiis), literally mean 'in the mountain passes'. This is nonsense, because the Bemelerberg east of Maastricht is a charming hill, not a mountain (it is not a confined space either). However, Tacitus plays a trick. From a Roman point of view, the Batavians were living on the edges of the earth, which consisted of forests and mountains. By mentioning mountain passes, he reminded the reader of the nature of the country, which could, in Roman thought, only produce savages.

After the battle of Maastricht, Julius Civilis moved to Atuatuca, modern Tongeren. Its inhabitants tried to prevent the destruction of their town by building a large wall, but in vain: Tongeren was sacked. After this, the support of the Tungrians, which Civilis had just gained, must have been less enthusiastic.