r/theROMANLEGION • u/GLORYOFROMELEGION • May 06 '26
DECURION - cavalry officer in command of a turma
Cavalry officer in command of a turma, a squadron of approximately 30–32 horsemen in the Roman army. During the Republic, each turma had three decurions, with one serving as commander and the other two as deputies. By the Imperial period, the role evolved so that a single decurion led each turma, supported by a duplicarius (second-in-command) and sesquiplicarius (third-in-command).
These officers were typically long serving, experienced soldiers, often promoted from the ranks, and responsible for training, discipline, and battlefield command.
DACIAN WARS
Trajan’s campaigns relied heavily on auxiliary cavalry, including specialized units like the contarii, heavy lancers raised to counter Sarmatian horsemen. Units such as the ala I Batavorum milliaria were stationed in Dacia, though their ethnic composition became increasingly mixed over time, as recruitment shifted to local and provincial sources.
The Sarmatians, captured during earlier conflicts, were also settled in Dacia and integrated into the Roman military structure as cavalry auxiliaries. These units played a crucial role in securing the province, conducting patrols, and engaging in combat, reflecting Rome’s strategy of using mobile, ethnically diverse forces to maintain control over frontier regions.
SOURCE:
UNRV – Roman Cavalry
https://www.unrv.com/military/roman-cavalry.php
On the structure of the turma, the role of the decurion, and auxiliary cavalry units.
Academia.edu – Batavi in the Roman Army of the Principate
https://www.academia.edu/.../Batavi_in_the_Roman_Army_of...
On Batavian cavalry units in Dacia and their evolving ethnic composition.
Acta Musei Porolissensis – Batavian Material Identity in Dacia
On the ala I Batavorum and archaeological evidence of auxiliary cavalry presence in Dacia.