Although Southminster is only 75 minutes' train ride from the middle of London, if you stand at St. Peter on the Wall, just a few miles away, you could think you were at the edge of the world. There is an eerie stillness and beauty to this spot like no other place I know.

The chapel of St Peter at Bradwell is built on the gatehouse of the Roman fort of Othona (or Ithancaster) by the Saxon Bishop Cedd in around 654 AD. Clearly this accounts for the "on the Wall" name, but it also recalls the fact that Othona was part of an Eastward-facing "wall" of shore fortifications as elaborate as Hadrian's Wall in the north.

The forts of the Saxon Shore as they were known, were built in the Third Century to give protection against Saxon sea-raiders, though they came to have a wider purpose, sometimes defending Roman Britain against hostile forces from the wider Empire.

The nine forts which survive were all on or near the sea, at strategic points guarding river estuaries, and with both a strong garrison and a small harbour from which a fleet could operate. They stretch from Brancaster in Norfolk to Portchester in Hampshire.

They were massive in scale, with walls over four metres thick in places (from study of the foundations at Bradwell) and nearly five metres high (from surviving structures at Burgh Castle). Heavy stone and bolt-throwing engines could be mounted on the towers, and the attached fleet would be alerted by the watchers on the towers and sail out to attack raiders going up the Blackwater or the Colne.

Unlike Burgh, Pevensey, Portchester and Richborough, which all have substantial remains, little is left of Othona except the foundations, although the chapel has clearly been built of reclaimed Roman stone, brick and tiles. The sea has also eroded the east wall of the fort, so we do not have the full ground plan, although the regular shape of these forts allows us to guess what is missing.

Coins found in excavations date from Emperor Gallienus (260-268) to Honorius (395-423), so the lonely garrison of Othona probably kept their watch for 150 years. Who were these soldiers? At this stage, it's likely that few would have come from Italy. A 5th Century record lists the garrison as a unit called "Numerus Fortensium", Numerus being the name for a regular army border force, and "Fortensium" being the nickname "brave ones".

These men would have come from all over the Roman empire, although as the empire declined soldiers tended to marry local girls from the community that grew up near each fort, and their children followed them into local military service. When Rome abandoned the province of Britain, generally dated as 410 AD, it's likely that most of these men would have stayed, and used the strong walls to protect their families and livestock in the increasing chaos of those times.

It's tantalising to think that the DNA of those Roman soldiers from far-flung corners of the empire may still live on in some of our Dengie residents!

Re-enactment photo courtesy of Britannia, www.durolitum.co.uk