Anderida

Anderitum
View from the castle inner bailey showing the outer Roman curtain wall
Anderitum Anderitum shown within East Sussex
OS grid reference	TQ645047
Coordinates	50°49′08″N 0°20′02″E / 50.8188°N 0.3338°E / 50.8188; 0.3338Coordinates: 50°49′08″N 0°20′02″E / 50.8188°N 0.3338°E / 50.8188; 0.3338
List of places UK England East Sussex

Anderitum (also Anderida, Anderidos) is a Saxon Shore Fort in the Roman province of Britannia. It is located at grid reference TQ645047 in eastern Pevensey in the English county of East Sussex and was later converted into a medieval castle known as Pevensey Castle.

The fort is named as Anderitum, apparently meaning "great ford", in the Notitia Dignitatum, a list of Roman "dignities" (i.e. public offices) as of the 5th century. (An alternative spelling of Anderida or Anderita has also been proposed, but is disfavoured.)

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 giving the place-names of Rickney, Horse Eye, North Eye and Pevensey. All are derived from the Old English word īeg, meaning island.

Unlike at many other Roman forts, no civilian settlement or vicus appears to have been established outside the walls of Pevensey Castle; this was probably because the fort was at the end of a peninsula with limited room for additional construction.

The fort's construction has been dated to around 290, based on the dating of wooden piles which were found underpinning the Roman walls in an excavation carried out in 1994. 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. The construction of the Saxon Shore forts has been linked to the raids that Saxon and Jute pirates (from what is now northern Germany and mainland Denmark) were mounting against communities along the North Sea and English Channel. An alternative explanation is that Anderitum was built to defend Roman Britain from Rome itself. Carausius, a Roman general who commanded the Classis Britannica (the Roman fleet based in the English Channel), revolted against Rome in 286 and declared himself emperor of Britain and northern Gaul. 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.