The Antonine Wall
The Emperor Antoninus Pius succeeded Hadrian in 138AD and decided to launch a new invasion of Caledonia. Advances to both the east and west, led by the governor Lollius Urbicus, saw a series of supply forts, roads and fortlets constructed on the routes up to the new frontier line of the Forth – Clyde isthmus with Trimontium acting as a key forward base for these operations. An early event in this invasion was the siege at Burnswark, in Dumfriesshire.
Construction on the Antonine Wall and its many forts and fortlets commenced around AD 142, briefly establishing a new frontier, but the wall was abandoned around 165AD, four years after the death of Antoninus Pious. The Romans fell back to Hadrian’s Wall although Trimontium continued to be occupied and remained an outpost of Rome within Caledonia until around 180AD when it seems the fort was evacuated although the reasons for this are unclear. What is known is that the native tribes were becoming more aggressive in their raids south as the Roman province of Britannia went through a period of revolt and instability.
In 195 Clodius Albinus, the Roman Governor of Britain, had led most of the British legions into Gaul during his revolt against the Emperor Septimius Severus. Severus had sent them back to their posts after defeating Albinus, but they had suffered large casualties at the Battle of Lugdunum. This left Hadrian’s Wall undermanned and made it easy for the Caledonians to raid into Roman Britain. The Caledonians were also able to gather more men for these raids than before as there is evidence of increased cooperation among the different northern tribes.