A powerful British chieftain who was defeated by Julius Caesar during Caesar's second raid of Britain in 54 BC. Cassivellaunus is the first man in England whose name we know and he led his tribe, the Catuvellauni, a group of Belgic invaders from the River Marne area. He used guerrilla tactics and chariot warfare successfully until Caesar captured the fortified settlement, identified as present-day Wheathampstead, Hertfordshire. Cassivellaunus agreed to provide hostages and pay an annual tribute to Rome, but there is no evidence that he kept these promises. His son was Cunobelin, the Cymbeline written about by Shakespeare.