Dux Britanniarum

Dux Britanniarum was a military post in Roman Britain, probably created by Emperor Diocletian or Constantine I during the late third or early fourth century.

The purpose of this buffer zone was to preserve the economically important and prosperous southeast of the island from attacks by the Picts (tribes of what are now the Scottish lowlands) and against the Scots (Irish raiders).

The Dux would have had considerable influence within his geographical jurisdiction, and exercised significant autonomy due in part to the distance from headquarters of his superiors.

[1] The Notitia Dignitatum lists the garrison along Hadrian's Wall (along with several sites on the coast of Cumbria) under the command of the Dux Britanniarum.

Fourteen units in north Britain are listed in the Notitia as being under his command, stationed in either modern Yorkshire, Cumbria or Northumberland.

One might expect that this legion (full name: Legio VI Victrix Pia Fidelis Britannica) at this time still to be stationed in Eburacum: this absence may indicate that the unit had been moved to another site when the list of the Dux Britanniarum was compiled in the Notita Dignitatum.

The men under the Praefectus Numbers Solensium could (per Arnold Hughes Martin Jones, 1986) be the descendants of another British unit, the Legio XX Valeria Victrix.