In A.D. 43 the Emperor Claudius set out to conquer Britain. A legion commanded by Vespasian moved west from Kent and soon the port of Clausentum was established.
Some scant remains can still be found in the Bitterne Manor area.
Traces of Roman roads to Winchester and Chichester have been discovered as has an altar stone to Ancastra, a local God.
After the Romans left in A.D. 410 the Saxons arrived and set up the settlement of Hamwih on the other side of the River Itchen.