The Tertia Herculea

This page created 1 August 2014, and last modified: 4 July 2015 (Maier reference numbers added)


One of the units of legiones comitatenses in the Magister Peditum's infantry roster is listed (98/9.112) as the Tertia Herculea; it is assigned (102/5.105) to the command of the Comes Illyricum. Its shield pattern (96#5) in various manuscripts, under the matching label (96.e), is as shown 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 shows a yellow main ground with a red rim. The boss is red in O & P, but white in M, W, & B, and is encircled with yellow (O, P, W) or white (M, B). Between the main ground and the boss is a band that is plain red in B, but in O, P, M, & W is multi-coloured, in red, yellow (white in M, W) and blue (yellow in W); this multi-coloured band is unique amongst the patterns illustrated in the Notitia.

The name Herculea indirectly refers to the demi-god Hercules, via the Tetrarchic emperor Maximian, i.e. Marcus Aurelius Valerius Maximianus Herculius. Maximian, like his colleague Diocletian, had many units named after him; examples still extent 100 years later in the Notitia include two incorprating the name Maximian, and 17 incorporating Herculea, Herculia, or Herculiani; many of the various units incorporating the name Valerian may also be named after him. Of the Herculean-named units, 6 are alae (mounted); of the infantry, 5 are (auxiliary) cohorts, and six are legionary.

Unlike most field army legionary units whose name incorporates a number, the Tertia Herculea appears to have no corresponding limitanei unit with a matching name and number. That its number is Tertia may indicate it was raised in (or for) a province that already had a second legion but not a third. The province of Valeria, created from Pannonia Inferior in 296, would appear to be a reasonable match, as Legio I Adiutrix and Legio II Adiutrix were stationed there, but Tetrarchic legions almost invariably came in pairs, so this is not as likely as would appear at first blush. In the Notitia, the Dux Valeriae ripensis commands a legionary prefect whose legion name is missing (143.43), which might just possibly be Legio III Herculea, but since there whereabouts of half of Legio I Adiutrix is also missing, this is to my mind a more likely candidate to fill the missing blank, especially given the half that is listed (143.29) also happens to be in Valeria. Another provincial candidate is Scythia, which in the Notitia has a Legio I Iovia (74.22-25) and a Legio II Herculia (74.19-21), but this again runs into the problem of being "extra". It may well be that the legion was created as a strategic reserve unit, as posited by E.C.Nischer in 1923 (available here or here); this hypothesis is certainly not weakened by the lack of corresponding limitanei units in the Notitia, and might imply it was transferred into the new comital field armies at an early stage of its existence. However, if this latter hypothesis is true, the unit's relatively low ranking would then be rather surprising. On the other hand, it is also possible that the Illyrian Tertia Herculea as recorded in the Notitia was only the rump left over after another detachment had been taken, much earlier, to form the elite Herculiani seniores (98/9.22). Vegetius (1.17) records "the" Illyrian Herculiani of the Tetrarchy as being 6000 strong, and it could thus have given rise to a number of detachments. Incidentally, Vegetius says the unit was renamed by Diocletian and Maximian rather raised by them - one should be alive to the possibility that any unit formed by the Romans might have been a more of a rebranding exercise involving one or more former units than enrolling a new body of men.


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