In 55 BC, Julius Caesar landed on the coast, in what was intended as a reconnaissance mission. During his campaigns in Gaul, as recorded in Gallic Wars, he had determined that the Gauls were receiving aid from Britain. Towards the end of the summer, he decided that it would be useful to get some reliable information about the people, localities and harbours of the island,
since little useful information was available from the Gauls or the merchants who visited it. First he sent out Caius Volusenus in a ship of war to investigate the coast, while in the meantime assembling a fleet of ships and settling an uprising by the Morini tribe of
Gaul. Within days he received ambassadors from British tribes, promising that they would give hostages and submit to the Romans. He received them favourably and sent them back with Commius of the Atrebates, whom he thought would be influentual in Britain. Volusenus reported back after five days.
Caesar's fleet comprised about 80 transport ships for two legions. He also had ships of war and 18 ships of burden for his cavalry. Caesar sailed for Britain with the legions, but did not land immediately,
since the British forces had gathered on the hills overlooking the shore and his cavalry had been delayed. After waiting at anchor for several hours, he sailed about seven miles to a place with an open shore. However the British, making heavy use of cavalry and chariots,
were able to follow the progress of the fleet and attacked the Romans as they attempted to land. The Romans were disadvantaged by the need to disembark in deep water due to the size of the ships, while the British attacked from the shallows. However the British were eventually driven back with projectiles fired from the ships of war and the Romans managed to land and drive them off. The Romans
established a camp and received ambassadors, and meeting again Commius who had been seized on arrival. Caesar demanded hostages: however a storm forced his still delayed cavalry back to the continent and many of his ships were damaged on the beach. With the Romans presumed to be disheartened and short of provisions, the British took the opportunity to renew the attack, ambushing one of the legions as it foraged near the Roman camp, making use of a form of cavalry attack that was novel to the Romans. However they were relieved by the remainder of the Roman force and the British were dispersed once again. After several days of storms, the British regrouped with
larger forces. On attacking the Romans they were once again defeated, with a large number killed in retreat and the Romans laying waste to the surrounding area. Once again the British sent ambassadors, this time Caesar demanded double the number of hostages, to be delivered to
Gaul (only two tribes eventually made good this promise). With the equinox drawing near, the Romans returned to Gaul.
In 54 BC, Caesar returned with a larger force. After taking hostages and receiving promises of tribute, Caesar returned to Rome.
The main (and most successful) invasion, occurred during the reign of the emperor Claudius. In AD 43, Aulus Plautius was appointed by Claudius as the general in charge of 4 Roman legions to invade Britain. The four legions were:
The main landing is thought to have been at Richborough in modern Kent in Southeast England; an increasing number of archaeologists are questioning the evidence for this, and believe that at least part of the force may have come via another route, eg. the Solent. British resistance was led by the sons of King Cunobelinus (Cymbeline in Shakespeare's play), Togidumnus and Caratacus. Emperor Claudius visited Britain briefly to take charge of the capture of Cunobelinus's capital, Camulodunum (modern Colchester). It is said he brought an elephant with him. After this defeat, Caratacus fled to the Welsh mountains and continued the fight against the invaders.
Britain was never fully conquered. The Roman occupation reached the River Clyde-River Forth area in AD 142 where the Antonine Wall was contructed before retreating to the earlier and more defensible Hadrian's Wall in the River Tyne-Solway Firth frontier area. This being previously constructed around AD 122.
Further Reading
Julius Caesar: 55 BC
Julius Caesar: 54 BC
Aulus Plautius: AD 43
These totalled about 20,000 men. In addition there were also about the same number of auxiliaries in the invasion force.