He was slain the year after the taking of Rome, that is A.C. 411, 14 Kal.

Octob. Whence the revolt was in Spring A.C. 408. Sozomen joins Constantine’s expedition into Gallia with Arcadius’ death, or the times a little after; and Arcadius died A.C. 408 May the 1st. Now though the reign of these Tyrants was but short, yet they gave a beginning to the kingdom of Britain, and so may be reckoned the three first Kings, especially since the posterity of Constantine, viz. his sons Aurelius Ambrosius, and Uther Pendraco, and his grandson Arthur, reigned afterwards. For from the time of the revolt of these Tyrants Britain continued a distinct kingdom absolved from subjection to the Empire, the Emperor not being able to spare soldiers to be sent thither to receive and keep the Island, and therefore neglecting it; as we learn by unquestionable records. For Prosper tells us; A.C. 410, Variane Cos. Hac tempestate prae valetudine Romanorum, vires funditus attenuatae Britanniae. And Sigebert conjoining this with the siege of Rome, saith: Britannorum vires attenuatae, & subtrahunt se a Romanorum dominatione. And Zosimus lib.6. The Transrhenane Barbarians invading all places, reduced the inhabitants of the island of Britain, and also certain Celtic nations to that pass, that they fell off from the Roman Empire; and being no longer obedient unto the Roman laws, , they lived in separate bodies after their own pleasure. The Britons therefore taking up arms, and hazarding themselves for their own safety, freed their cities from the imminent (immanent?) Barbarians. In like manner all Brabant and some other Provinces of the Gauls imitating the Britons, freed themselves also, ejecting the Roman Presidents, and forming themselves into a sort of commonwealth according to their own pleasure. This rebellion of Britain and the Celtic nations happened when Constantine usurped the kingdom.