The Roman Army A to Z: legio

legio (f. pl. legiones, Ang. ‘legion’)

A legion, comprising around 5,000 legionarii in nine cohortes (II to X) of six centuriae, and one (I) of five double-strength centuriae. Commanded by a legatus (Augusti) legionis, with the tribunus legionis laticlavius as his deputy. Third in command was the praefectus castrorum, with the tribuni legionis angusticlavi under him and the primus pilus next. At any one time, there were twenty-five to thirty-three legions in the Imperial period (c.125,000 to 165,000 men) (Tac., Ann. 4.5; Cass. Dio 55.23; CIL VI, 3492); l. comitatensis: a legion in the mobile field army of the Late Roman period (ND Occ. 5; Or. 7); l. palatina: a legion in the units of the Late Roman period (ND Occ. 5; Or. 5). [Keppie 1984; Goldsworthy 2003]