Caesar's approach towards Britain in 54 BCE was far more comprehensive and successful than his initial expedition. New ships had been built over the winter, and Caesar now took five legions and 2,000 cavalry. He left the rest of his army in Gaul to keep order. Gilliver notes that Caesar took with him a good number of Gallic chiefs whom he considered untrustworthy so he could keep an eye on them, a further sign that he had not comprehensively conquered Gaul.

Determined not to make the same mistakes as the previous year, Caesar gathered a larger force than on his previous expedition with five legions as opposed to two, plus two thousand cavalry, carried in ships which he designed, with experience of Venetic shipbuilding technology so as to be more suitable for a beach landing than those used in 55 BCE, being broader and lower for easier beaching. This time he named Portus Itius as the departure point.

Titus Labienus was left at Portus Itius to oversee regular food transports from there to the British beachhead. The military ships were joined by a flotilla of trading ships captained by Romans and provincials from across the empire, and local Gauls, hoping to cash in on the trading opportunities. It seems more likely that the figure Caesar quotes for the fleet (800 ships) include these traders and the troop-transports, rather than the troop-transports alone.

Caesar landed without resistance and immediately went to find the Britonic army. The Britons used guerilla tactics to avoid a direct confrontation. This allowed them to gather a formidable army under Cassivellaunus, king of the Catuvellauni. The Britonic army had superior mobility due to its cavalry and chariots, which easily allowed them to evade and harass the Romans. The Britons attacked a foraging party, hoping to pick off the isolated group, but the party fought back fiercely and thoroughly defeated the Britons. They mostly gave up resistance at this point, and a great many tribes surrendered and offered tribute.