The military conquest of Wales proved no easy task even for a Roman army regarded as the best in the ancient world. Thirteen separate military campaigns over around 30 years, involving up to 30,000 Roman soldiers were needed before the stubborn resistance of the Britons was finally overcome.
The early success of the army was largely due to their speedy construction of forts and roads. At first temporary ‘marching camps’ were put up and then permanent forts were built to garrison conquered territory. Two of the four legionary fortresses in Britannia were built in or near Wales, one at Deva (Chester) and the other at Isca (Caerleon). An earlier legionary fortress built at Burrium (Usk) in around AD 55 was probably a base for the XXth legion. However, when the legion was moved to Viroconium (Wroxeter), probably in the later 60s AD, the Usk fortress was downgraded and manned by a much smaller force. As well as these fortresses, the Romans built a network of auxiliary forts linked by roads.
The legions were not only a military force. They also assisted in the construction of towns and roads and set up manufacturing centres. Several sites which made pottery for the army have been found like those at Caerleon and at Holt in Wrexham.

