Britannia Prima or Britannia I (Latin for "First Britain") was one of the provinces of the Diocese of "the Britains" created during the Diocletian Reforms at the end of the 3rd century. It was probably created after the defeat of the usurper Allectus by Constantius Chlorus in  296 and was mentioned in the  Verona List of the Roman provinces. Its position and capital remain uncertain, although it was probably located closer to Rome than Britannia II. At present, most scholars place Britannia I in Wales, Cornwall, and the lands connecting them. On the basis of a recovered inscription, its capital is now usually placed at Corinium of the Dobunni (Cirencester) but some emendations of the list of bishops attending the 315 Council of Arles would place a provincial capital in Isca (Caerleon) or Deva (Chester), which were known legionary bases.