Togodumnus is known only from Dio Cassius's Roman History, according to which he was a son of Cunobelinus. He probably succeeded his father to the kingship of the Catuvellauni, who were the dominant kingdom in the south-east of Britain at this time. Their territory took in the lands of several other nations, including their neighbours the Trinovantes, and possibly the Dobunni further west.
He had two notable brothers, Adminius and Caratacus. In Cunobelinus's later days Adminius gained control of Kent, but was driven from Britain in 40 AD, seeking refuge with the Roman Emperor Caligula. Caligula planned an invasion of Britain in response, but called it off at the last minute.
Based on coin distribution it appears that Caratacus, following in the footsteps of his uncle Epaticcus, completed the conquest of the Atrebates, the main rival to the Catuvellauni, in the early 40s. The Atrebatian king, Verica, fled to Rome and gave the new emperor, Claudius, a pretext to conquer Britain in 43.
According to Dio's account, Togodumnus led the initial resistance to the invasion, but was killed after the battle on the Thames. The Roman commander Aulus Plautius then dug in at the Thames and sent word for Claudius to join him for the final march on the Catuvellaunian capital, Camulodunum (Colchester). Dio says that this was because the resistance became fiercer as the Britons tried to avenge Togodumnus, and Plautius needed the emperor's help to complete the conquest; however as Claudius was no military man, and in the end spent only sixteen days in Britain, it is likely the Britons were already as good as beaten. Leadership passed to Caratacus, who took the fight outside Roman-controlled territory and remained at large until 51.
Togodumnus is nearly contemporary with Tiberius Claudius Cogidubnus (or Togidubnus), a pro-Roman king of the Regnenses in the period after the Roman conquest, who is known from Tacitus's Agricola and an inscription found in Chichester. The similarity of their names has led some, including the distinguished archaeologist Barry Cunliffe, to suggest that they may be one and the same. However the sources do not support this: according to Dio, Togodumnus was killed in 43, while Tacitus says that Cogidubnus remained loyal to Rome into the later part of the 1st century, and his inscription dates after 79. It is of course not unusual in for two people to have similar names (cf. Dubnovellaunus). As the Chichester inscription supports Tacitus, Cunliffe's interpretation would appear to imply an error in Dio's Roman History or in its transmission.
| Preceded by: Cunobelinus | King of the Catuvellauni | Succeeded by:<br.>Caratacus |