Other Saxon Shore forts were built or reconstructed around this time as part of a systematic programme of improvements to the coastal defences of Roman Britain.

He was assassinated in 293 by his treasurer, Allectus, who was himself killed in 296 when the Roman emperor Constantius Chlorus invaded Britain to overthrow the usurper.

[8] Anderitum appears to have been a key link in the Saxon Shore forts, which extended from Hampshire to Norfolk and may have been connected by intermediate watchtowers.

Like the other Saxon Shore forts, Anderitum's position at a strategic harbour would have enabled the Romans to control access to the shoreline and prevent invaders from penetrating inland.

[11] The amount of construction material required was very large, equating to about 31,600 cubic metres (1,120,000 cu ft) of stone and mortar.

An excavation in 1906–08 found shattered tiles stamped HON AUG ANDRIA, which were used to attribute Pevensey Castle's construction to the reign of the early 5th century Emperor Honorius.

[15] Anderitum is recorded in the Notitia Dignitatum as the base of the praepositus numeri Abulcorum – an infantry unit or numerus of the limitanei or border forces.

It is not known whether their name is a geographical or functional one but their description by Zosimus suggests that they were an elite body of troops, who served both in the field army and, probably in the form of a single detachment, at Anderitum.

[17] They may have been foederati, troops raised from allied barbarian tribes and put under the command of a Roman prefect, or perhaps even a single band of warriors with their own leader.

[18] Following the Roman withdrawal from Britain, local Romano-British civilians took over the fort, and the Latinized Celtic name continued to be used well into the Saxon period.

This year came Ælle to Britain, with his three sons, Cymen, and Wlenking, and Cissa, in three ships; landing at a place that is called Cymenshore.

[10] When William the Conqueror launched his invasion of England by landing at Pevensey Bay on 28 September 1066, his army sheltered for the night in a temporary fortification within the old Roman fort.