In the Spring of 70, Julius Civilis was at the zenith of his power. Frisians, Cananefates, the Cugernians of Vetera, the Ubians of Cologne, the Tungrians of Tongeren, and the Nervians all recognized the superiority of the Batavians, and in the south, the Lingones and Trevirans were fighting against Rome as well. However, since Civilis had attacked Vetera, it was certain that the Romans would sent a large army to the north.
Its commander was an old war horse named Quintus Petillius Cerialis, not only a relative of the new emperor Vespasian, but also his companion in the British wars, where he must have met Julius Civilis as well.
The expeditionary force consisted of the victorious Eighth legion Augusta, the Eleventh Claudia and Thirteenth Gemina, the Twenty-first Rapax (which had been one of those supporting Vitellius), and, of the recently recruited legions, the Second Adiutrix. These were led across the Alps by the Great St Bernard and Mont Genevre passes, though part of the army took the Little St Bernard. The Fourteenth legion Gemina was summoned from Britain, and the Sixth Victrix and First Adiutrix from Spain.
Not all these legions saw action. The Eighth legion merely went from Italy to Strasbourg, where several units may already have been guarding the Rhine. The Eleventh was left behind in Vindonissa (modern Windisch) in Germania Superior. The British and the two Spanish legions first had to pacify parts of Gaul, and arrived late.
So, the army of Cerialis in fact consisted of only three legions, II Adiutrix, XIII Gemina, and XXI Rapax. Nonetheless, it was a powerful army that inspired fear. The army of Civilis' ally Julius Tutor (above) disintegrated even before Cerialis arrived: the former legionaries in Tutor's service returned to their original allegiance, and the soldiers of the two legions that had capitulated, I Germanica and XVI Gallica, did the same. Seeing his enemy collapse in front of him, Cerialis advanced to Mainz, where he found the legions IIII Macedonica and XXII Primigenia (May 70).