Four days after landing the Roman fleet bringing the cavalry to Britain was decimated by a violent storm. The storm also damaged the fleet used for the initial landing. Most ships were damaged leaving the Roman army in a vulnerable position with low troop numbers and no stores for winter. Caesar salvaged equipment from damaged ships and sent to Gaul for naval supplies. To get food he sent out gathering parties to farms in the area for corn. During one of these missions he lost most of a legion to an ambush by the local Britons.
By 56 AD Caesar had reached the Thames near what is now London. In the Iron age London was at the confluence of maritime trade routes. It is entirely a Roman city with no earlier settlements found. Cotton remarks that the Invasion commander, Julius Caesar made no mention of an existing site in London, although there were other abandoned sites nearby:
“Caesar makes no mention of any major settlements (‘oppida’) in the area in the mid-50s BC, yet archaeology has demonstrated the existence of large enclosed sites along the lower Thames valley at Uphall Camp, Ilford, and Woolwich Arsenal. John Kent’s suggestion – again based on coin distributions – that there may have been a major centre somewhere on the Thames west of London (Kent 1978) also looks prescient in the context of finds coming to light in the Barn Elms/Putney reaches. But the evidence, such as it is, suggests that these sites had fallen from use by the 80s BC and therefore prior to Caesar’s expeditions in mid-century.” (Cotton. 2016)
Contrary to popular belief there were roads in Britain prior to the Romans. This is evidenced by Iron age carvings of four wheeled wagons. After consolidating in the South the Romans headed North on both sides of the Pennines.
In 78 AD Agricola began the invasion of the North. At this time a small fort was established at Walton Le Dale. This was on the road from Wigan to Lancaster. It was also close to a river crossing, the lowest point where this was possible.