It was sound reasoning, but it implied some riske for the garrison at Vetera, which was commanded by the Munius Lupercus we already met above. The siege started at the end of September 69.
The arrival of the veteran auxiliary units meant that Civilis now commanded a proper army. But he still hesitated on his course of action, and reflected that Rome was strong. So he made all the men he had swear allegiance to Vespasian, and sent an appeal to the two legions which had been beaten in the previous engagement [above] and had retired to the camp at Vetera, asking them to accept the same oath.
Back came the reply. They were not in the habit of taking advice from a traitor nor from the enemy. They already had an emperor, Vitellius, and in his defense they would maintain their loyalty and arms to their dying breath. So it was not for a Batavian turncoat to sit in judgment on matters Roman. He had only to await his deserts - the punishment of a felon.
When this reply reached Civilis, he flew into a rage, and hurried the whole Batavian nation into arms. They were joined by the Bructeri and Tencteri, and as the tidings spread Germany awoke to the call of spoil and glory.
Thus started the siege of Vetera. Some 5,000 legionaries, belonging to the already defeated Fifth legion Alaudae and Fifteenth legion Primigenia, defended their camp. Tacitus mentions the presence of the commander of the Sixteenth legion Gallica, which shows that Vetera had been reinforced with men from Neuss. However this may be, the Romans were in the minority. The Batavians had good reason to be optimistic, not in the least because they possessed eight well-trained units, and because Julius Civilis had been training his men along Roman lines. (It is too romantic to think of the revolt as a war between barbarian Batavians and disciplined Romans. In fact, two Roman armies were fighting each other.)
The camp at the Fürstenberg near Vetera was large (56 hectares) and modern - it was only ten years old and well-equipped. Archaeologists have discovered the walls (made of mud brick and wood), foundations of wooden towers, and a double ditch. Besides, the garrison had had time to prepare itself. Tacitus frequently mentions the Roman artillery, which must have possessed a lot of ammunition. He also states that there were no food supplies, which is a bit strange, briefly after the harvest season. In fact, Vetera held out for two months.
The Batavians and their allies first attempted to storm the walls of Vetera, but in vain. Then, they attempted to build siege installations, but they did not have the necessary knowledge. Nonetheless, it shows that they were fighting a 'Roman' war, using Roman siege techniques. Ultimately, Civilis decided to starve the two legions into surrender.
During the siege, Civilis sent out units to plunder towns in Germania Inferior and Gallia Belgica. Germans from the east bank of the Rhine joined in.
The Batavian leader ordered the Ubians and Trevirans to be plundered by their respective neighbors, and another force was sent beyond the Maas to strike a blow at the Menapians and Morinians in the extreme north of Gaul. In both theaters, booty was gathered, and they showed special vindictiveness in plundering the Ubians because this was a tribe of German origin which had renounced its nationality and preferred to be known by a Roman name.
In other words, the northern part of the Roman empire was in a state of turmoil. Tacitus plays a very subtle game in these lines. The words 'the Menapians and Morinians in the extreme north of Gaul' [Menapios et Morinos et extrema Galliarum] contain a reference to a well-known line by the poet Virgil, who had called the Morinians the extremi hominum, 'those living on the extreme edges of the earth' (Aeneid 8.727). By using these words, Tacitus remembered his reader of the well-known fact that this was a war against the most savage of all barbarians, which, as every Roman knew, lived on the edge of the world.