[3] Caesar eventually penetrated into Middlesex and crossed the Thames, forcing the British warlord Cassivellaunus to pay tribute to Rome and setting up Mandubracius of the Trinovantes as a client king.

Caesar included accounts of both invasions in his Commentarii de Bello Gallico, which contains the earliest surviving significant eyewitness descriptions of the island's people, culture and geography.

In the highlands, north of the line between Gloucester and Lincoln, arable land was available only in isolated pockets, so pastoralism, supported by garden cultivation, was more common than settled farming, and communication was more difficult.

Commercial contact between Britain and the continent had increased since the Roman conquest of Transalpine Gaul in 124 BC, and Italian wine was being imported via the Armorican peninsula, much of it arriving at Hengistbury Head in Dorset.

It appears that Belgic power was concentrated on the southeastern coast, although their influence spread further west and inland, perhaps through chieftains establishing political control over the native population.

[11] Strabo says that the Venetic rebellion in 56 BC had been intended to prevent Caesar from travelling to Britain and disrupting their commercial activity,[12] suggesting that the possibility of a British expedition had already been considered by then.

He probably examined the Kent coast between Hythe and Sandwich, but was unable to land, since he "did not dare leave his ship and entrust himself to the barbarians",[16] and after five days returned to give Caesar what intelligence he had managed to gather.

[17] These ships may have been triremes or biremes, or may have been adapted from Venetic designs Caesar had seen previously, or may even have been requisitioned from the Veneti and other coastal tribes.

Clearly in a hurry, Caesar himself left a garrison at the port and set out "at the third watch" (well after midnight) on 23 August[15][18] with the legions so that they would arrive at dawn, leaving the cavalry to march to their ships, embark, and join him as soon as possible.

In light of later events, leaving without the cavalry was either a tactical mistake or (along with the fact that the legions came over without baggage or heavy siege gear)[19] confirms the invasion was not intended for complete conquest.

[23] Recent archaeology by the University of Leicester indicates that the likely landing beach was at Ebbsfleet in Pegwell Bay where artefacts and massive earthworks dating from this period have been exposed.

If Caesar had as large a fleet with him as has been suggested, then it is possible that the beaching of ships would have been spread out over a number of miles stretching from Walmer towards Pegwell Bay.

Caesar claims he was negotiating from a position of strength and that the British leaders, blaming their attacks on him on the common people, were in only four days awed into giving hostages, some immediately, some as soon as they could be brought from inland, and disbanding their army.

Realising this and hoping to keep Caesar in Britain over the winter and thus starve him into submission, the Britons renewed the attack, ambushing one of the legions as it foraged near the Roman camp.

This attack was driven off fully, in a bloody rout, with improvised cavalry that Commius had gathered from pro-Roman Britons and a Roman scorched earth policy.

Taking an understrength army with few provisions to a far-off land was a poor tactical decision, which easily could have led to Caesar's defeat, yet he survived.

The Britons attacked but were repulsed, and attempted to regroup at a fortified place in the forests, possibly the hillfort at Bigbury Wood, Kent,[27] but were again defeated and scattered.

However, the next morning, as he prepared to advance further, Caesar received word from Atrius that, once again, his ships at anchor had been dashed against each other in a storm and suffered considerable damage.

The Romans were unused to Atlantic and Channel tides and storms, but nevertheless, considering the damage he had sustained the previous year, this was poor planning on Caesar's part.

Disbanding the majority of his force and relying on the mobility of his 4,000 chariots and superior knowledge of the terrain, he used guerrilla tactics to slow the Roman advance.

By the time Caesar reached the Thames, the one fordable place available to him had been fortified with sharpened stakes, both on the shore and under the water, and the far bank was defended.

Second Century sources state that Caesar used a large war elephant, which was equipped with armour and carried archers and slingers in its tower, to put the defenders to flight.

[31] The Trinovantes, whom Caesar describes as the most powerful tribe in the region, and who had recently suffered at Cassivellaunus' hands, sent ambassadors, promising him aid and provisions.

Five further tribes, the Cenimagni, Segontiaci, Ancalites, Bibroci and Cassi, surrendered to Caesar, and revealed to him the location of Cassivellaunus' stronghold, possibly the hill fort at Wheathampstead,[32] which he proceeded to put under siege.

This is evidenced via the next identifiable king of the Trinovantes, known from numismatic evidence, was Addedomarus, who took power c. 20–15 BC, and moved the tribe's capital to Camulodunum.

[35] John Creighton believes that this anecdote was a legend,[36] and that Commius was sent to Britain as a friendly king as part of his truce with Mark Antony.

As well as noting elements of British warfare, particularly the use of chariots, which were unfamiliar to his Roman audience, Caesar also aimed to impress them by making further geographical, meteorological and ethnographic investigations of Britain.

Caesar's first-hand discoveries were limited to east Kent and the Thames Valley, but he was able to provide a description of the island's geography and meteorology.

By Claudius's time Roman knowledge of the island would have been considerably increased by a century of trade and diplomacy, and four abortive invasion attempts.

Caesar made no conquests in Britain, but his enthroning of Mandubracius marked the beginnings of a system of client kingdoms there, thus bringing the island into Rome's sphere of political influence.