Dux

A late Roman frontier commander, ancestor of the medieval duke and the word dux bellorum of Arthurian legend.

Overview

Dux, Latin for leader, from ducere, to lead, was a Roman title for any commander, but in the late empire it named the officer commanding the frontier troops of a province, the dux limitis, holding cavalry and infantry in a fixed border district. The title evolved into the medieval dux and then duke as frontier commands became hereditary lordships, one of the clearest survivals of Roman rank into feudal nobility. In the sixth century the war leader Arthur is called dux bellorum, leader of battles, in the earliest sources. The rank shows how military titles ossify into aristocratic ones across the fall of Rome.