Turma (pl turmae) was a division of the Roman cavalry of the time of the Republic and the Roman Empire.
In the 3rd and 2nd centuries BCE, during the Punic Wars and the Roman expansion into what is now Spain and Greece, the core of the army was formed by the citizens of Rome and supplemented by contingents of Roman allies (socii). The organization of the Roman legion of this period was described by Polybius, who mentions that for each legion there were 4,200 infantry and 300 civic cavalry (equites). This quota was divided into 10 turmae. The soldiers of such a detachment chose 3 decuriones (“leaders of 10 men”), the first elected was the commander-in-chief of the detachment and the other two were his deputies.
In the time of Octavian Augustus and his successors, the Roman army was reorganized. Turma became the basic cavalry unit and the equivalent of an infantry centurion. Turma was still commanded by decurio, supported by two principales: a soldier and a half wages (sesquiplicarius) and a soldier with double wages (duplicarius). He was also helped by signifer or vexillarius (soldiers carrying banners).
The exact size of the turma is not known. At the time of the Republic, 30 people were the norm. The work “De Munitionibus Castrorum” also mentions 24 soldiers, while Flavius Arrian speaks of 32 people.
During the Principate, the legion had one cavalry contingent, consisting of four turmae. The legionary turma was commanded by a centurion, fought by optio and vexillarius as an elder of principales. Each of them commanded a detachment of 10 people.
The form and structure of turma was preserved during the late empire.