The death of the Celtic warrior chief Cymbeline in AD 43, changed the face of British politics. The once powerful Catuvellauni tribe, which had ruled the British heartland for nearly a hundred years, became fractured and vulnerable. Other Celtic tribes rose-up against them, attempting to break free of their previous submission. One notable in this rebellion was King Verica, the leader of the Atrebates who lived in what is now Hampshire. Unable to defeat the Catuvellauni, he sent word to Roman requesting aid.
Meanwhile, Roman politics was also going through a shake-up. With the sudden death of Emperor Caligula, the unlikely Tiberius Claudius Drusus had taken the title of Emperor. Possessing few of the qualities of a classic Emperor, Drusus was looking for a way to prove himself to his people. When King Verica's appeal arrived, it seemed the perfect answer.
For several years, Britain had been close to Roman thinking, and at least one previous invasion had been planned. Now, Emperor Drusus organized a new expedition led by Aulus Plautius. The invasion force contained four full Roman legions (possibly as many as 20,000 troops) and nearly as many auxiliaries. This force crossed the channel and landed unopposed in the vicinity of modern day Richborough.
The first goal of the army was to take the Catuvellauni capital of Camulodunum. Several battles were fought, most notably at the crossings of the rivers Medway and Thames, but the Roman legions and their experienced auxiliaries brushed aside all resistance. With the army within striking distance of the capital, they stopped and awaited the arrival of the Emperor. Emperor Drusus arrived with reinforcements (possibly including the first elephants seen in Britain) and, with his army, seized Camulodunum. With the fall of the capital, many Celtic tribes submitted to the Roman army.
Emperor Drusus remained in Britain for about two weeks in order receive submissions and oversee the beginning of construction of a temple dedicated to himself. He then returned to Rome to receive his triumph.
As soon as the Emperor left, the Roman army continued military operations. Very little is known about this phase of the conquest, however by AD 47 the Romans were firmly in control of most of what is presently considered England (except parts in the north). It is also worth noting, that during this time, the Romans established a new center of operations for their British campaigns on a hilltop overlooking the Thames. This fortress city would soon become known as Londinium (though the name is Pre-roman and perhaps even pre-Celtic).
Although the Romans had added a big piece of Britain to their empire, the Celts still had a lot of fight left in them.
