Cassivellaunus

Cassivellaunus was a historical British military leader who led the defence against Julius Caesar's second expedition to Britain in 54 BC. He led an alliance of tribes against Roman forces, but eventually surrendered after his location was revealed to Julius Caesar by defeated Britons.

Cassivellaunus made an impact on the British consciousness. He appears in British legend as Cassibelanus, one of Geoffrey of Monmouth's kings of the Britons, and in the Mabinogi, Brut y Brenhinedd and the Welsh Triads as Caswallawn, son of Beli Mawr.

The Common Brittonic personal name Cassiuellaunos stems from the word uellaunos ('chief, commandant'). The meaning of the prefix cassi- has been debated, but it possibly signifies 'tin, bronze'. Cassivellaunus may thus been translated as 'Chief-of-Tin', that is to say 'the inflexible'. The personal name Ver-cassivellaunus ('True-Chief-of-Tin') is related.

Cassivellaunus appears in Julius Caesar's Commentarii de Bello Gallico, having been given command of the combined British forces opposing Caesar's second invasion of Britain. Caesar does not mention Cassivellaunus's tribe, but his territory, north of the River Thames, corresponds with that inhabited by the tribe named the Catuvellauni at the time of the later invasion under Claudius.

Caesar tells us that Cassivellaunus had previously been in near-constant conflict with his neighbours, as was typical of the British tribes in this period, and had recently brought down the king of the Trinovantes, the most powerful tribe in Britain at the time. The king's son, Mandubracius, fled to Caesar in Gaul. Despite Cassivellaunus's harrying tactics, designed to prevent Caesar's army from foraging and plundering for food, Caesar advanced to the Thames. The only fordable point was defended and fortified with sharp stakes, but the Romans managed to cross it. Cassivellaunus dismissed most of his army and resorted to guerilla tactics, relying on his knowledge of the territory and the speed of his chariots.

Five British tribes, the Cenimagni, the Segontiaci, the Ancalites, the Bibroci and the Cassi, surrendered to Caesar and revealed the location of Cassivellaunus's stronghold. (Possible sites include Hexton and the Devil's Dyke, Wheathampstead.) Caesar proceeded to put the stronghold under siege. Cassivellaunus managed to get a message to the four kings of Kent, Cingetorix, Carvilius, Taximagulus and Segovax, to gather their forces and attack the Roman camp on the coast, but the Romans defended themselves successfully, capturing a chieftain called Lugotorix. On hearing of the defeat and the devastation of his territories, Cassivellaunus surrendered. The terms were mediated by Commius, Caesar's Gallic ally. Hostages were given and a tribute agreed. Mandubracius was restored to the kingship of the Trinovantes, and Cassivellaunus undertook not to wage war against him. All this achieved, Caesar returned to Gaul where a poor harvest had caused unrest. The Roman legions did not return to Britain for another 97 years.

The Greek author Polyaenus relates an anecdote in his Stratagemata that Caesar overcame Cassivellaunus's defence of a river crossing by means of an armoured elephant. This claim may derive from a confusion with the Roman conquest of 43 AD, when Claudius is supposed to have brought elephants to Britain.

Cassivellaunus appears in Geoffrey of Monmouth's 12th-century work Historia Regum Britanniae (History of the Kings of Britain), usually spelled Cassibelanus or Cassibelaunus. The younger son of the former king Heli, he becomes king of Britain upon the death of his elder brother Lud, whose own sons Androgeus and Tenvantius are not yet of age. In recompense, Androgeus is made Duke of Kent and Trinovantum (London), and Tenvantius is made Duke of Cornwall.