had replaced the year before. They conspired to overthrow the emperor and seat Justinian in his place. The conspiracy failed, however, and Sophia was reduced to a modest allowance; Justinian was forgiven by Tiberius. The ongoing success against the Persians in the East once again allowed Tiberius to turn his gaze westward. In 579, he again extended his military activities into the remnants of the Western Roman Empire. He sent money and troops to Italy to reinforce Ravenna and to retake the port of Classis. He formed an alliance with one of the Visigothic princes in Spain, who was fomenting rebellion, and his generals defeated the rebellious Berbers under their king Garmul in North Africa. He also intervened in Frankish affairs in the former province of Gaul, which had been largely free of imperial contacts for close to a century. Consequently, he might have been the basis for the fictional emperor Lucius Tiberius of Arthurian legend, who sent envoys to former Roman provinces after a long period without an imperial presence. The reality, however, was that the empire was seriously overextended. In 579, with Tiberius occupied elsewhere, the Avars decided to take advantage of the lack of troops in the Balkans by besieging Sirmium. At the same time, the Slavs began to migrate into Thrace, Macedonia and southern Greece, which Tiberius was unable to halt as the Persians refused to agree to a peace in the east, which remained the emperor's main priority. Furthermore, the army of the East was beginning to become restless, as it had not been paid, and it threatened to mutiny. In 580, General Maurice launched a new offensive, raiding well beyond the Tigris. The following year, he again invaded Persian Armenia and almost succeeded in reaching the Persian capital, Ctesiphon, before a Persian counterinvasion of Byzantine Mesopotamia forced him to withdraw in order to deal with that threat. By 582, with no apparent end to the Persian war in sight, Tiberius was forced to come to terms with the Avars, and he agreed to pay an indemnity and to hand over the vital city of Sirmium, which the Avars then looted. The migration of the Slavs continued, with their incursions reaching as far south as Athens. Although a new Persian invasion was halted with a significant defeat at Constantina in June 582, by now, Tiberius was dying, apparently having eaten some poorly-prepared or possibly-deliberately poisoned