The Roman army is depicted as accurately as possible in the story, just as in the Vindolanda trilogy, but there is much that is guesswork and more detail can be found on my website and in books such as my The Complete Roman Army. Epigraphic evidence as well as logic suggest that a legion would have had an unusually high proportion of veterani some twenty years after its initial formation, although it is far less clear what was done with these men for the last period of their military service. In later centuries the frumentarii expanded their duties far beyond the organisation of supplies and became a form of secret police, bringing information to the emperor about the activities of his officers in the provinces. Hadrian is credited with starting this process, so there seemed no harm in suggesting that the idea had already occurred to him long before he became emperor.

Ferox is fictional, as is the irregular unit of Brigantes placed under his command. Such tribal units were increasingly common in the early second century AD; Trajan’s Column depicts bare-chested barbarians wielding clubs fighting alongside regular auxiliaries as well as legionaries. In later years the vague term of numerus or unit was often associated with these regiments, but at the time of our story they were usually referred to by an ethnic designation and listed as ‘under the care of’ (sub cura) a named commander. Little is known of their internal organisation and equipment, and there is a good chance that such units varied considerably, being composed and organised to meet a local need or simply on the basis of available manpower.

Ferox will be familiar to readers of my Vindolanda trilogy, as will Vindex, Enica, Philo and co, and the story of the Brigantian rebellion. Sadly all are fictional, as are the majority of the men at the fort and elsewhere. Sulpicia Lepidina and her husband Cerialis were real, attested in the Vindolanda writing tablets, although their stories have been considerably fleshed out in my novels. No trace of their lives has survived for the years before they came to Vindolanda and after they left. A Lucius Tettius Crescens is recorded on an inscription from Sardinia, noting that he was merchant in Dacia at the time of the war. A centurion and Roman citizen named Petrullus is recorded a generation later as having come from Britannia, so our Petrullus is meant to be his father whose loyal service gained the family the franchise.

Maximus – fully Tiberius Claudius Maximus – is known from his tombstone, which records his career as a legionary cavalryman, who subsequently rose to become a decurion of auxiliary cavalry, serving as standard-bearer, a member of the acting governor’s bodyguard and scout along the way. He led the party that chased down Decebalus at the end of the Second Dacian War, and is depicted on his own monument and on Trajan’s Column riding forward just as the king slits his own throat. Highly decorated, Maximus’ career appears less distinguished than might be expected, which may suggest that he was one of those soldiers very good at fighting, but perhaps less suited to peacetime routine.