The Romans followed the Atuatuci while they fled and besieged their oppidum. Upon the first arrival of the Roman army, the Atuatuci made frequent sallies from the stronghold, and engaged in petty encounters with Roman troops. According to Caesar, the inhabitants initially laughed at the Roman work, since their siege-towers, mantlets, and ramparts were being erected far from the oppidum and, Caesar follows, the Atuatuci remarked the incongruity of such a large device being constructed by such small men. As they saw the Roman troops approaching the settlement with siege weapons, however, the Atuatuci offered to surrendered. Caesar accepted, and they opened the gates of their fortress.