The Tertiodecimani

This page created 23 March 2014, and last modified: 13 April 2014 (Galerian picture added)


The Tertiodecimani is listed as one of the Legiones comitatenses under the Magister Militum per Thracias. Its shield pattern, under the label "Tertio decimani" or "Tertio Decimani", is shown in various manuscripts as below:

Tertiodecimani shield patterns

Disclaimer: remember, I'm not an expert in the field of Notitia studies, so take my comments with a grain of salt...

Note that five detachments of this unit appear to be commanded by prefects under the Dux Daciae ripensis, under the title "Praefectus legionis tertiaedecimae geminae"; they are stationed at Aegeta, Transdrobeta, Burgo Novo, Zernis, and Ratiaria, respectively. They are clearly descended from the old Legio XIII Gemina, which had been stationed at Ratiaria after Aurelius withdrew from Dacia. Another detachment appear under the Comes limitis Aegypti as the "Legio tertiadecima gemina", stationed at Babilona.

Three other Legiones comitatenses units under the Magister Militum per Thracias, the the Quartodecimani, the Constantini seniores, and the Divitenses Gallicani, have very similar patterns to that of the Tertiodecimani, as can be seen below from the following patterns taken from the Paris manuscript:

Shield patterns

Given the seemingly unrelated nature of the names of units, this suggests a simultaneous issuance when all four were perhaps detached from their parent units to join a new formation (such as that of the Magister Militum per Thracias).

The image of an eagle above a central ring (which would thus surround a shield's boss) brings to mind the Arch of Galerius, where an eagle grasping a wreath of victory is shown other Galerius' (defaced) head:

Tertiodecimani shield patterns

One must wonder why the Tertiodecimani alone of these four units does not feature such an eagle. The old Legio XIII Gemina had a lion as its legionary badge, but the animal on the shield of the Tertiodecimani looks more like a dog, so making a connection between the two unlikely.


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