"The other order is that of the knights. These, when there is occasion and any war occurs (which before Caesar's arrival was for the most part wont to happen every year, as either they on their part were inflecting injuries or repelling those which others inflected on them), are all engaged in war. And those of them most distinguished by birth and resources, have the greatest number of vassals and dependents about them. They acknowledge this sort of influence and power only."
Caesar - De bello Gallico (about the Gallic war) VI.15.1-2.
Translated by W. A. McDevitte. & W. S. Bohn.