The fort of the largest unit on Hadrian’s Wall, the double-strength cavalry unit of ala Petriana, is poorly understood and has not produced the volume of inscriptions of some smaller forts elsewhere. Paradoxically, none of the inscriptions actually mentions the unit, although a cavalryman is depicted on one of the tombstones.
RIB 2025: Matribu[s d]/omesticis [s]/uis Asin[ius] / S[e]nili[s] v(otum) s(olvit) l(ibens) [m(erito)] (‘For his household mother goddesses, Asinius Senilis willingly and deservedly fulfilled a vow’). Altar found before 1725 and taken to Scelby Castle. Source: RIB I p.620
RIB 2026: Dedica[ta] / Imp(eratore) Vero [III et] / Um(m)idio [Quadrato] / [co(n)s(ulibus)] (‘Dedicated in the consulship of the Emperor Verus, for the third time, and of Um(m)idius Quadratus’). Altar fragment found in 1931 W of the fort. Source: RIB I p.620
RIB 2027: Leg(io) VI / Vic(trix) p(ia) f(idelis) / G[o]r(diana) r[e]f(ecit) (‘Sixth Legion Victrix Pia Fidelis Gordiana rebuilt this’). Building stone found 1599 (at Stanwix?). Source: RIB I pp.621-2
RIB 2028: Leg(ionis) XX Vic(tricis) / coh(ors) I fecit (‘Twentieth Legion (Valeria) Victrix, the First Cohort built this’). Building stone found before 1794 at Stanwix. Source: RIB I p.622
RIB 2029: Dis Manibu/s Marci Troiani / Augustini tit(ul)um fa/ciendum curavi/t Ael(ia) Ammillusima / coniux kariss(ima) (‘For the immortal shades, for Marcus Troianius Augustinus his most beloved wife Aelia Ammillusima had this tombstone set up’). Tombstone found at Stanwix in 1599, now at Drawdikes Castle. Source: RIB I p.621
RIB 2030: [D]i[s] Manibus / [… (‘For the immortal shades…’). Tombstone found in 1787 built into Stanwix church, now at Netherhall. Source: RIB I p.621
The building inscriptions imply the construction in stone of the (originally turf-and-timber) fort by the Twentieth Legion (2028) and its refurbishment by the Sixth (2027) in AD 238–44, but this may be an over-simplistic interpretation. It is certainly salutary that no inscription names the unit in garrison, ala Petriana (which is named in the Notitia Dignitatum). The cavalry tombstone (2030), of the traditional ‘rider’ type showing a barbarian foe being trampled, leaves little room for doubt about a mounted presence here.