The Rhine enters the Netherlands in the east, and divides itself into three rivers. The southern branch is the Waal and passes along Nijmegen; the middle one is the Rhine; and in the north is the IJssel. Originally, the IJssel was not a branch of the Rhine, but Drusus had cut a canal and built a large mole that made sure that water flowed into this canal. After the construction of the mole, the Rhine was the largest of the three branches. Now that Civilis had destroyed the mole, the southern branch, the Waal, became the largest of the three rivers (it still is). Since the Batavians lived between the Waal and the Rhine, his measure had as result that their country had a southern border that was hard to transgress - one of the broadest rivers in Europe.
Cerialis knew that he could not cross the river without navy, and decided to wait until he did have a fleet. Meanwhile, his soldiers had to guard the river. The Sixth and Twenty-first legions were sent to Neuss and Bonn, the Twenty-second Primigenia came from Mainz to Vetera; the Second started to built a bridge at Nijmegen, the Tenth went to an unidentified place called Arenacium. Auxiliary units were stationed at Grinnes and Vada - also unidentified.
Meanwhile, the Romans were occupied with the reconstruction of the Rhineland. Julius Civilis attempted to attack four camps at the same time -he himself attacked Vada, his ally Julius Classicus Grinnes- but the Batavians had underestimated the velocity and effectiveness of the Roman response. Cerialis arrived quickly, and Civilis had to swim across the Rhine to save his life.
A few days later, the Batavians were able to tow away the flagship of the newly built Roman flotilla during a surprise raid, but had to discover that Cerialis was not on board. (He spent the night with a woman from Cologne.) The ship was sent to the Bructerian prophetess Veleda.
It was humiliating, and Cerialis decided that he could no longer postpone the invasion of the Betuwe, the Island of the Batavians. His ships were now ready, and the navy seems to have invaded the Island from the west, whereas Cerialis crossed the Waal near Nijmegen in the southeast.
Cerialis ravaged the Island of the Batavians severely, employing the well-known stratagem of leaving Civilis' land and farms untouched. But by this time Summer was turning to Autumn, and repeated rainstorms at the equinox [August 30] caused the rivers to inundate the marshy, low-lying island until it looked like morras. Nor was there any sign of the Roman fleet or convoys in the offing, and the camps on the flat ground were being washed away by the violence of the river.
It was later claimed by Civilis that the legions could have been crushed at this moment, and he took credit for cunningly diverting the Batavians from this aim when they were set upon it. This may be true, since a few days later, he surrendered.