Having distinguished himself by his military ability and his able and gentle rule of Dalmatia, he was, on the 1 st of March 293, adopted and appointed Caesar by Maximian, whose step-daughter, Flavia Maximiana Theodora, he had married in 289 after renouncing his wife Helena (the mother of Constantine).
72 made a province by the Romans, and its capital received the additional name of Flavia (Suet.
In the 5th century there were five provinces, Britannia Prima and Secunda, Flavia and Maxima Caesariensis and (for a while) Valentia, ruled by praesides and consulares under a vicarius, but the only thing known of them is that Britannia Prima included Cirencester.
Vespasian made it a colony and called it Flavia: the old name, however, persisted, and still survives as Kaisarieh.
Vespasian, as a reward for its having taken his part, gave the town part of the territory of Capua, and installed more colonists there - whence it took the title Colonia Flavia, which it retained till the end of the empire.