I'm not sure where you get the word "Anglescae" from. In fact, the first Google hit I get is this very thread.

Anyway, here is Caesar's description of the Belgae in De Bello Gallico:

Gallia est omnis divisa in partes tres, quarum unam incolunt Belgae [...]. Horum omnium fortissimi sunt Belgae, propterea quod a cultu atque humanitate provinciae longissime absunt, minimeque ad eos mercatores saepe commeant atque ea quae ad effeminandos animos pertinent important, proximique sunt Germanis, qui trans Rhenum incolunt, quibuscum continenter bellum gerunt.

All Gaul is divided into three parts, one of which the Belgae inhabit [...]. Of all these, the Belgae are the bravest, because they are furthest from the civilization and refinement of [our] Province, and merchants least frequently resort to them, and import those things which tend to effeminate the mind; and they are the nearest to the Germans, who dwell beyond the Rhine, with whom they are continually waging war.

I'm not sure why someone would translate the word "fortissimi" as "ugliest". The translation above, sourced from here gives it as "bravest".

Googling Van Amerongen tells me he's Dutch - do you have the Dutch word he uses where you say "ugliest"? Did he say "lelijkst"? Or something more figurative?