The Romans evenually conquered Britain in AD 43, during the reign of Claudius. Forty thousand men landed in Kent and quickly began to make their presence felt by taking Colchester, a major tribal capital. Of the four legions who arrived on our shores, IX Hispana travelled north and came to the place we know today as Lincoln.
Historic Lincoln at this time lay within the area of the Iron Age tribe called Corieltauvi and traces of an Iron Age settlement have been found on the east bank of the Brayford Pool. The Romans, understanding the military advantage of the site, built a fortress on top of the hill, a strategic position over looking the River Witham and the major trackways around Lincoln. The Legion IX Hispana occupied Lincoln from about AD 54 -71 but some time after AD 71, the IX Legion left for York and was replaced by Legion II Adiutrix, who remained in Lincoln until AD 78.
During the military occupation it was important for the Romans to keep order and control. To do this effectively, forts were established enabling troops quick access to the troublesome areas. Unfortunately only few have remains that can be seen. The best examples are at Horncastle and Caistor. Both towns are late 4th Century walled towns (possibly military), directly linked with a pre-Roman route recognised today as the B1225.