On the next day the Fourteenth legion were sent to join Annius 19 Gallus[533] in Upper Germany, and their place in Cerialis' army was filled by the Tenth from Spain. Civilis was reinforced by the Chauci.[534] Feeling that he was not strong enough to hold the Batavian capital,[535] he took whatever was portable with him, burnt everything else, and retired into the island. He knew that the Romans had not enough ships to build a bridge, and that they had no other means of getting across. He also destroyed the mole built by Drusus Germanicus.[536] As the bed of the Rhine here falls towards Gaul, his removal of all obstacles gave it free course; the river was practically diverted, and the channel between the Germans and the island became so small and dry as to form no barrier between them. Tutor and Classicus also crossed the Rhine,[537] together with a hundred and thirteen town-councillors from Trier, among whom was Alpinius Montanus, who, as we have already seen,[538] had been sent by Antonius Primus into Gaul. He was accompanied by his brother. By arousing sympathy and by offering presents, the others, too, were all busy raising reinforcements among these eagerly adventurous tribes. The war was far from being over. Dividing his forces, Civilis 20 suddenly made a simultaneous attack on all four Roman garrisons--the Tenth at Arenacum, the Second at Batavodurum, and the auxiliary horse and foot at Grinnes and at Vada.[539] Civilis himself, Verax his nephew, Classicus and Tutor each led one of the attacking parties. They could not hope all to be successful, but reckoned that, if they made several ventures, fortune would probably favour one or the other. Besides, Cerialis, they supposed, was off his guard; on receiving news from several places at once he would hurry from one garrison to another, and might be cut off on his way. The party told off against the Tenth considered it no light task to storm a legion, so they fell on the soldiers, who had come outside to cut timber, and killed the camp-prefect, five senior centurions, and a handful of the men. The rest defended themselves in the trenches. Meanwhile another party of Germans endeavoured to break the bridge[540] which had been begun at Batavodurum, but nightfall put an end to the battle before it was won.