Phase 5 (c.140-158AD): As the Roman presence pressed northwards and work began on the Antonine Wall (from 142AD), the role for Trimontium changed. It was reduced in size with the building of a 2m thick masonry wall through the main fort, though at the same time stone was used in the rebuilding. Manufacturing was becoming an important role for this newly purposed supply and logistics centre. Now behind the front line it is believed that the civilian population attached to the fort may have numbered some 2–3,000.