Legioni

Legioni is the Italian plural form of legione, a term used to denote a large military unit in ancient Rome, and more broadly to refer to similarly organized formations in other contexts. In Latin, the corresponding singular is legio and the plural legiones. The word lineage traces back to Rome’s military institutions, while in Italian today it may describe both historical legions and modern organizational groupings that use the same naming convention.

In antiquity, a Roman legion was a principal unit of the legiones, typically comprising about 4,800 to 6,000 infantry and, at times, accompanying cavalry. Legions were commanded by a legatus legionis and structured into ten cohorts, with the first cohort often being the largest and most prestigious. Each cohort contained centuries of soldiers led by senior centurions. The composition, training, and equipment of legions evolved under different Republican and Imperial reforms, including Augustus’s standardization of equipment and command. Legions also included engineers, specialists, and later auxiliary forces that augmented Roman military capacity.

Historically notable legions include Legio X Equestris, led by Julius Caesar, and Legio IX Hispana, known from sources as a legion that disappears from records in the early 2nd century. Legio XII Fulminata, or “the Thunderbolt,” is another frequently cited unit. The concept of legions influenced military organization for centuries and remains a reference point in studies of Roman warfare.

In modern Italy, the term legione (plural legioni) persists in some institutions to denote regional commands or large organizational formations, such as regional units within the Carabinieri. The historical legio therefore continues to shape both academic and public understandings of ancient military organization.