Conspiracy of barbarians – barbarian invasion of Britain in 4th century CE
According to the Roman historian Ammianus Marcellinus, an event called barbarica conspiratio (“barbarian conspiracy”) took place in the second half of the 4th century CE, which involved a simultaneous attack on Roman Britain by various barbarian tribes. It is not clear whether this was an organized action; however, it certainly severely damaged the province, which was abandoned by the Romans half a century later.