Trahern () is a legendary
King of the Britons in
Geoffrey of Monmouth's fictional ''
Historia Regum Britanniae
(''The History of the Kings of Britain''), originally called (''On the Deeds of the Britons''), is a fictitious account of British history, written around 1136 by Geoffrey of Monmouth. It chronicles the lives of the List of legendary kings o ...
''.
According to Geoffrey, Trahern was king of the
Britons and
Roman senator. He was the brother of the late
Coel Hen
Coel (Old Welsh: ''Coil''), also called ''Coel Hen'' (Coel the Old) and King Cole, is a figure prominent in Welsh literature and legend since the Middle Ages. Early Welsh tradition knew of a Coel Hen, a 4th-century leader in Roman Britain, Ro ...
and uncle of
Saint Helena. Trahern was sent by Emperor
Constantine I
Constantine I (27 February 27222 May 337), also known as Constantine the Great, was a Roman emperor from AD 306 to 337 and the first Roman emperor to convert to Christianity. He played a Constantine the Great and Christianity, pivotal ro ...
to restore
Britain to
Roman rule during the usurpation of Octavius (
Eudaf).
When Octavius took control of Britain from Rome, Constantine sent three
Roman legion
The Roman legion (, ) was the largest military List of military legions, unit of the Roman army, composed of Roman citizenship, Roman citizens serving as legionary, legionaries. During the Roman Republic the manipular legion comprised 4,200 i ...
s to Britain under the command of Trahern. He landed at 'Kaerperis' and captured it forcing Octavius to conscript all the island into the army to combat the Roman legions.
Octavius met Trahern in a field outside
Winchester
Winchester (, ) is a City status in the United Kingdom, cathedral city in Hampshire, England. The city lies at the heart of the wider City of Winchester, a local government Districts of England, district, at the western end of the South Downs N ...
where they fought and Octavius won.
Trahern fled to
Albany and pillaged the land. That caused Octavius to react again, where he met Trahern in
Westmorland
Westmorland (, formerly also spelt ''Westmoreland''R. Wilkinson The British Isles, Sheet The British IslesVision of Britain/ref>) is an area of North West England which was Historic counties of England, historically a county. People of the area ...
, but Octavius was defeated this time. Octavius fled Britain and Trahern took on the crown himself. A few years later, supporters of Octavius, who was in exile in
Norway
Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...
, attacked Trahern in a forest. They killed him and Octavius immediately returned and was recrowned king.
References
{{Geoffrey of Monmouth
British traditional history