optio: the second in command of a century of eighty men and deputy to a centurion.

pilum: the heavy javelin carried by Roman legionaries. It was about 6 to 7 feet long. The shaft was wooden, topped by a slim iron shank ending in a pyramid-shaped point (much like the bodkin arrow used by longbowmen). The shank was not meant to bend. Instead the aim was to concentrate all of the weapon’s considerable weight behind the head so that it would punch through armour or shield. If it hit a shield, the head would go through, and the long iron shank gave it the reach to continue and strike the man behind. Its effective range was probably some 15 to 16 yards.

praesidium: the term meant garrison, and could be employed for a small outpost or a full-sized fort.

prefect: the commander of most auxiliary units was called a prefect (although a few unit COs held the title tribune). These were equestrians, who first commanded a cohort of auxiliary infantry, then served as equestrian tribune in a legion, before going on to command a cavalry ala.

procurator: an imperial official who oversaw the tax and financial administration of a province. Although junior to a legate, a procurator reported directly to the emperor.

scorpion (scorpio): a light torsion catapult or ballista with a superficial resemblance to a large crossbow. They shot a heavy bolt with considerable accuracy and tremendous force to a range beyond bowshot. Julius Caesar describes a bolt from one of these engines going through the leg of an enemy cavalryman and pinning him to the saddle.

seplasiarius (or seplasiario): military pharmacist working in a fort’s hospital.

signifer: a standard-bearer, specifically one carrying a century’s standard or signum (pl. signa).

Silures: a tribe or people occupying what is now South Wales. They fought a long campaign before being overrun by the Romans. Tacitus described them as having curly hair and darker hair or complexions than other Britons, and suggested that they looked more like Spaniards (although since he misunderstood the geography of Britain he also believed that their homeland was closer to Spain than Gaul).

spatha: another Latin term for sword, which it is now conventional to employ for the longer blades used mainly by horsemen in this period.

stationarii: soldiers detached from their parent units and stationed as garrison elsewhere, often in a small outpost.

tesserarius: the third in command of a century after the optio and signifer. The title originally came from their responsibility for overseeing sentries. The watchword for each night was written on a tessera or tablet.

tribune: each legion had six tribunes. The most senior was the broad-stripe tribune (tribunus laticlavius), who was a young aristocrat at an early stage of a senatorial career. Such men were usually in their late teens or very early twenties. There were also five narrow-stripe or junior tribunes (tribuni angusticlavii).