From 340 onwards, northern Britain was repeatedly attacked by Picts and Gaels. In 360, a large-scale attack forced the emperor Julian the Apostate to send troops to deal with the problem. Large efforts were made to improve Londinium's defenses around the same time. At least 22 semi-circular towers were added to the city walls to provide platforms for ballistae and the present state of the river wall suggested hurried repair work around this time. In 367, the Great Conspiracy saw a coordinated invasion of Picts, Gaels, and Saxons joined with a mutiny of troops along the Wall. Count Theodosius dealt with the problem over the next few years, using Londinium—then known as "Augusta"—as his base. It may have been at this point that one of the existing provinces was renamed Valentia, although the account of Theodosius's actions describes it as a province recovered from the enemy.