Anderitum (also Anderida or Anderidos) was a Saxon Shore fort in the Roman province of Britannia. The ruins adjoin the west end of the village of Pevensey in East Sussex, England. The fort was built in the 290s and was abandoned after it was sacked in 471 (491 according to the disputed Anglo-Saxon Chronicles). It was re-inhabited by Saxons and in the 11th century the Normans built a castle within the east end of the fort. The site decayed to become the archetypal ruinous medieval castle, Pevensey Castle, which is surrounded by a small moat, large green, and unusually substantial Roman defensive walls on three sides. During the Second World War, the Roman fort and medieval castle were adapted for modern warfare, and pillboxes were built into the Roman walls. Etymology The fort is named Anderidos or Anderitos in the Notitia Dignitatum, and Anderida was formerly the most accepted form. This has been interpreted as a Latinized version of the Celtic ande- (an intensive prefix) and ritu- (British element meaning "a ford", as in the Modern Welsh rhyd and Cornish ryd), giving a translation of "Great Ford". Andred persisted as a name into the Saxon period, with the wooded area surrounding the fort becoming known as Andredes Weald, meaning "The Forest of Andred". As the original name was adopted into English, it is thought the Romano-British culture at Anderitum persisted in the forest after the Saxon occupation, and the Anglo Saxon Chronicle records "Wealas" (Welshmen, or Romanized Britons) in the woods. Location The fort was built on what was then peninsula of land rising above the coastal marshes. The sea washed over what is now Pevensey Marshes surrounding Anderida on three sides, so giving a safe and sheltered landing point. This marshy inlet of the sea, extending inland as far as Hailsham, was studded with small areas of high land which remained as islands at high tide so later giving the place-names of Rickney, Horse Eye, North Eye and Pevensey derived from the Old English word īeg, island. Unlike at many other Roman forts, no civilian settlement or vicus appears to have been established outside its walls; this was probably because the fort was at the end of a peninsula with limited room for additional construction. Dating The fort's construction has been dated to around 290, based on the dating of wooden piles which were found underpinning the Roman walls