Mandubracius or Mandubratius was a king of the Trinovantes of south-eastern Britain in the 1st century BC. History Mandubracius was the son of a Trinovantian king, named Imanuentius in some manuscripts of Julius Caesar's De Bello Gallico, who was overthrown and killed by the warlord Cassivellaunus some time before Caesar's second expedition to Britain in 54 BC. Mandubracius fled to the protection of Caesar in Gaul. Cassivellaunus then led the British defence against the Romans, but the Trinovant… (More on Mandubracius)