The Decima gemina

This page created 8 April 2014, and last modified: 26 July 2015 (Ammianus reference numbers added)


In the eastern half of the empire, the 4th of the nine units of legiones comitatenses listed (15.19 in Ingo Maier's numbering scheme) as being under the command of the Magister Militum per Orientem is called the Decima gemina. Its shield pattern (14#1) as shown in various manuscripts, under the matching label (14.a) Decima Gemina, is as below:

shield patterns

Disclaimer: Remember, a lot of what comes below is speculation. Hopefully informed speculation, but speculation nonetheless. Comments welcome! (lukeuedasarson "at"

The pattern has a yellow boss (white in M), encircled by a blue band and then a yellow band (white in M); the main field is blue and decorated (except in B) with 8 devices in black that resemble sprouting plants. The shield pattern is thus very similar to that of the previous unit listed under the same commander, that of Septima gemina (15.18), as can be seen below from the following patterns taken from the Paris manuscript:

Shield patterns

Decima gemina is clearly a detachment of the Legio X gemina, famed in Caesar's day, and long stationed in Vindomarae (Vienna), where a detachment is still recorded (145.13) in the Notitia, under the Dux Pannoniae primae et Norici ripensis. Septima Gemina, on the other hand, is clearly a detachment of Legio VII Gemina, founded in 68 AD, and long stationed in Leon, in Spain (and indeed, where a detachment is still recorded in the Notitia, (156/8.44), so the fact they have very similar sheild patterns implies they had some more modern relationship together - perhaps being transferred at the same time into the command of the Magister Militum per Orientem, or perhaps slightly earlier, when other units that eventually found their way into the command were moved into Macedonia, such as the Secunda Flavia Constantia Thebaeorum (15.22).

Also shown above is the only other similar pattern in the Notitia, that of the Iulia Alexandria (18.29), one of the legiones comitatenses under the Magister Militum per Thracias. The name of this unit suggests it was raised by the emperor Severus Alexander (whose powerful mother was named Julia) early in the 3rd century, and it may have got its pattern at the same time as the Septima Gemina and the Decima gemina.

In addition to the detachment at Vindomarae, another detachment of Legio X gemina under the Dux Pannoniae primae et Norici ripensis is stationed (145.15) at Arrabona (Gyor, Hungary), and whose Prefect also commands a detachment of Legio XIIII Gemina.

The Decima gemina is presumably the Legio Decimani identified by Ammianus (18.9.3) as being at the siege of Amida, where it was just one of seven defending "legions", although Ammianus' text has it has come down to us may have been corrupted, for apparently 8 units are listed, not 7: Legiones V Parthica, Magnetiaci, Decentiaci, Tricensimani, Decimani, Fortenses, Superventores, & Praeventores. It has been proposed that the text be amended to "Decimanique Fretenses", thereby reducing the number of legions by one, and also turning Ammianus' 10th into a descendent of Legio X Fretensis rather than Legio X gemina.


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