AWA409 - What did the Constitutio Antoniniana mean for the Roman auxilia?

This episode of Ancient Warfare Answers explores the impact of the Constitutio Antoniniana (212 CE) on the Roman auxilia, addressing a question from listener Carlos, an economics professor and Hispania-born historian. Murray explains that while the edict granted Roman citizenship to all freeborn inhabitants of the empire—potentially reducing the appeal of the auxilia by allowing more men to join the legions—the auxilia persisted due to continued recruitment of non-citizens, including barbarian 'numerii' and enslaved or non-freeborn populations. Despite the legions' prestige, many citizens still enlisted in auxilia units for cultural, familial, or practical reasons, preserving unit identities like the Batavians well into the fourth century. Murray highlights that the distinction between legions and auxilia blurred under Diocletian's reforms, with the creation of new structures like the auxilia palatina and limitani, yet named units endured due to tradition and legacy. The episode concludes with reflections on how the concept of 'freeborn' citizenship limited the reform's reach, and how the auxilia remained vital through the turbulent third century and beyond, even participating in the Battle of Adrianople.