Four legions took part in the initial invasion: Leg. II Augusta, Leg. XIIII Gemina, Leg. XX Valeria, and Leg. IX Hispana. It is possible that vexillatores (detachments) from other legions also joined. Including their auxiliary force, the Romans had some 40,000 troops gathered at the Gallic coastal town of Gesoticum. There was some delay caused most probably by the superstitious fears of the troops. When the army did cross the channel they found their landing zone (in modern-day Kent) totally undefended. It is thought that the Roman delay convinced the British that the invasion had been postponed until the next campaigning season. Or perhaps the demands of the harvest required their army to disperse. In any case, the Romans quickly took advantage of the situation, forming a beach head and pushing in to the interior. The British, avoided a pitched battle until the Roman force reached a river (most probably the Medway). At this point the British tribes set up camp opposite the Romans, secure in the knowledge that the Roman army would be unable to cross the river with much success. The Romans, however, found a ford some distance up the river and sent across Leg. II Augusta (probably commanded by the future emperor, Vespasian). While this legion was sneaking up on the British flank, a troop of Batavian auxiliary cavalry was sent as a diversion across the river in plain view of the British. This in itself surprised the Brits. The British chariot horse were unhitched, making them ideal targets for the advancing cavalry. Although they lost heir chariot arm, and Leg. II Augusta did catch them off guard, the British managed to hold their own until nightfall.
The next day Leg. XX Valeria commanded by C. Hosidius Geta crossed the river, followed by the remainder of the Roman forces. They succeeded in defeating the British forces, who fell back to the River Thames. It was normal Roman practice to follow up a defeat by sending their cavalry to slaughter the broken formations of fleeing enemy. At this point in time the land around the river was very marshy, making it very difficult for the cavalry to pursue. The overall, commander, Plautius was ordered to halt his advance in order to give the Emperor Claudius time to make an appearance and grab some glory. At his arrival, the Romans proceeded to lay siege to the Catuvellauni tribal capital of Camuldunon. Togodumnus, one of the two brother leading the tribe had been killed in the previous battle. Feeling ill-prepared, the remaining brother, Caratacus, decided to flee the Romans to Whales. It is believed that there really was not much British resistance after the fall of the capital. Claudius received the submission of eleven British kings and Vespasian and his legion were put in charge of the clean-up operations. By 84 AD, Rome had a firm grasp on the island, and would not let go until the 400's AD.
1. Warriors of Rome, by Michael Simkins
2. Eagles over Britannia, by Guy de la Bedoyere
3. AD 43: The Roman Invasion of Britain, by John Manley
4. The Roman Invasion of Britain, by Graham Webster