ALA—a cavalry regiment, orginally 500 to 1,000 men, divided into 16 or 24 squadrons respectively.
AQUILIFER—the officer carrying the Eagle, the sacred insignia of the legion.
AUXILIARIES—originally provincial troops formed into cavalry regiments (alae) or infantry regiments (cohorts) 500 to 1,000 strong; later troops of the frontier army.
BALLISTA—a type of artillery for throwing heavy missiles. These varied in size and performance. The smaller ones were often called scorpions or onagers.
CARROBALLISTA—a type of mobile field artillery which fired 9 to 12 inch bolts with iron heads.
CENTURION—usually the officer commanding a century; a rank for which there is no modern equivalent.
CENTURY—the smallest unit (100 men) of the legion which originally contained 60 centuries.
COHORT—originally a tactical unit of the legion comprising six centuries; also an auxiliary regiment.
COMES GALLIARUM—Comes (Count) was an honorary title often conferred upon senior military and civil officers. In some instances the title carried special duties.
COUNT OF THE SAXON SHORE—(Comes Littoris Saxonici) the general commanding the defences of the south-east coast of Britain.
CURATOR—a civilian official who fulfilled the functions of a mayor.
CURIAL CLASS—the provincial class from which municipal and local government officers were selected.
DECURION—a junior officer in an auxiliary cavalry unit commanding a troop.
DUX—the commander in chief of a provincial army.
LEGION—originally a brigade of troops, 6,000 strong, commanded by a legate and recruited solely from Roman citizens. In the late empire the legion was smaller, was commanded by a praefectus and was part of the frontier army.
LIMES—a military frontier.
MASTER OF HORSE—(Magister Equitum) a subordinate general commanding all the imperial cavalry. The Magister Equitum per Gallias was the general commanding the Field Army of Gaul.
MILITARY MASTER—(Magister Militum) the general officer commanding all the imperial troops.
OPTIO—an officer junior to a centurion; often his second in command.
PRAEFECTUS—a general term for civil or military officials holding posts of varying degrees of responsibility.
PRAEFECTUS PRAETORIO—a civil official responsible directly to the emperor for the administration of a group of provinces.
QUAESTOR—a civilian official, often in charge of finance.
TRIBUNE—a senior officer of the legion; also an officer of the civil administration.
VALLUM—a broad ditch running the length of Hadrian’s Wall on the south side, defining the area under control of the military.
VICARIUS—the governor under the Praefectus Praetorio immediately responsible for the administration of a group of provinces.