When Caesar inquired of them what states were in arms, how powerful they were, and what they could do, in war, he received the following information: that
the greater part of the Belgae were sprung, from the Germans, and that having crossed the Rhine at an early period, they had settled there, on account of the fertility of the
country, and had driven out the Gauls who inhabited those regions; and that they were the only people who, in the memory of our fathers, when all Gaul was overrun, had prevented the Teutones and the Cimbri from entering their territories; the effect of which was, that, from the recollection of those events, they assumed to themselves great authority and haughtiness in military matters. Book 2, 4