 During the chaotic years of the reign of Valerian, Illyria was the only province, generaled by such officers as Claudius, Aurelian and Probus, where the barbarians were kept at bay, while Gaul was overrun by the Franks, Rhaetia by the Alemans, Thrace and the Mediterranean by the Goths, and the east by Shapur I. Probus became amongst the highest placed lieutenants of Aurelian, reconquering Egypt from Zenobia in 273 A.D. Emperor Tacitus, upon his accession in 275, appointed Probus supreme chief of the east, granting him extraordinary powers in order to secure a dangerous frontier.Though the details are not specified, he is said to have fought with success on almost every frontier of the empire, before his election as emperor by the troops upon Tacitus' death of old age in 276, in his camp in Asia Minor.Florianus, the half-brother of Tacitus, also proclaimed himself emperor, and took control of Tacitus' army in Asia Minor, but was killed by his own soldiers after an indecisive campaign against Probus in the mountains of Cilicia.