But the fortune of war changed. Civilis attempted to surprise the camp of Gelduba; the attack began successfully, and the defection of the cohorts of the Nervii brought Vocula's little band into a critical position. Then suddenly two Spanish cohorts fell on the rear of the Germans; what threatened to be a defeat was converted into a brilliant victory; the flower of the assailing army remained on the field of battle. Vocula indeed did not advance at once against Vetera, as he possibly might have done, but he penetrated into the besieged town some days later after a renewed vehement conflict with the enemy. It is true that he brought no provisions; and, as the river was in the power of the enemy, these had to be procured by the land-route from Novaesium, where Flaccus was encamped. The first convoy passed through; but the enemy, having meanwhile assembled again, attacked the second column with provisions on its way, and compelled it to throw itself into Gelduba. Vocula went off thither to its support with his troops and a part of the old garrison of Vetera. When they had arrived at Gelduba, the men refused to return to Vetera and to take upon themselves the further sufferings of the siege in prospect; instead of this they marched to Novaesium, and Vocula, who knew that the remnant of the old garrison of Vetera was in some measure provisioned, had for good or evil to follow. [Sidenote: Mutiny of Roman troops.] In Novaesium meanwhile mutiny had broken out. The soldiers had come to learn that a largess destined for them by Vitellius had reached the general, and compelled its distribution in the name of Vespasian. They had scarcely received it, when, in the wild carousing which ensued upon the largess, the old grudge of the soldiers broke out afresh; they pillaged the house of the general who had betrayed the army of the Rhine to the general of the Syrian legions, slew him, and would have prepared the same fate for Vocula, if the latter had not escaped in disguise. Thereupon they once more proclaimed Vitellius emperor, not knowing that he was already dead. When this news came to the camp, the better part of the soldiers, and in particular the two upper German legions, began in some measure to reflect; they again exchanged the effigy of Vitellius on their standards for that of Vespasian, and placed themselves under the orders of Vocula; he led them to Mentz, where he remained during the rest of the winter 69-70. Civilis occupied Gelduba, and thereby cut off Vetera, which was most closely blockaded; the camps of Novaesium and Bonna were still held. [Sidenote: Insurrection in Gaul.]