Castra Brigetio
About
Legio I Adiutrix ('Loyal and Faithful'), raised by Nero/Galba from Ravenna fleet marines in 68 CE, was moved from Moguntiacum (Mainz) to Pannonia c. 86-92 CE under Domitian and Brigetio became its long-term home (into the 4th c.). CAVEAT: the legion fought in Trajan's Dacian and Parthian Wars (101-106, 114-117), and multiple sources state it was 'sent back to Pannonia, with base in Brigetio' specifically by Hadrian after Trajan's death (r. from 8 Aug 117) — meaning that at the exact 117 CE snapshot the legion itself was very likely still with the field army in the East (Syria/Mesopotamia/Cappadocia, exact camp unattested) or in transit, only physically reoccupying Brigetio c. 118 CE. Brigetio's garrison in 117 CE proper was Legio XXX Ulpia Victrix (see separate entry), which held the fortress from 105 until it ceded it to the returning I Adiutrix and moved to Vetera in 122. Pinned here as I Adiutrix's essentially-continuous permanent fortress (pre- and post-Parthian War) with the transfer gap flagged.
What happened here
A legionary fortress holds five thousand men and is laid out to the same plan everywhere, so a transferred soldier knows his way around on the first day. Two main streets cross at the headquarters building, where the standards and the pay chest are kept in a sunken strongroom under guard. Around it: the commander's house with a courtyard garden, granaries raised on stone piers, a hospital, workshops, and long barrack blocks divided into rooms for eight men who cook and mess together. Training is daily, and building work is constant — soldiers make their own bricks, tiles and boots. A civilian town grows against the walls, with bars, traders and the unofficial families of men who are not legally allowed to marry.
Sources
Roman Maps shows the empire frozen at 11 August 117 CE, the day Trajan died — its moment of greatest territorial extent. Explore the full map →