Riduna: Alderney in the Roman Empire

Jason Monaghan

Alderney was part of the Roman Empire for over 400 years. It was one of the islands called the InsulaeLenuri and was known as Riduna. Not much was known about Romans in the Channel Islands until the 1980’s when Roman buildings were found in St Peter Port and a shipwreck was raised from its harbour. At least four more Roman shipwrecks are now suspected around Guernsey. Jersey also had the remains of a small temple

The Romans commanded by Julius Caesar conquered the nearby coasts of Gaul in 56BC. Guernsey may already have been friendly to the Romans before this as ships had been stopping there carrying Roman pottery and wine possibly as early as 120BC. Guernsey was on the route taken by merchant ships sailing up the Atlantic Coast of Gaul and into the Channel. Most would have avoided Jersey as it did not have a good harbour and was ‘in the corner’ surrounded by dangerous reefs. Alderney’s rocks and currents were also to be avoided. Ancient sailors however liked to sail in sight of land so it is likely they would have used Alderney as a navigation point when sailing north from Guernsey, or south out of the Channel.

Roman objects found in the islands came from modern France, Germany, Britain, Spain, Italy, North Africa and Palestine. Trade goods included olive oil and fish sauce carried in amphorae (large jars).Each style of amphora came from a different region and experts have worked out what many of them carried.

Remains of Roman buildings have been found two metres under the sand at Longis Common. Longis was a natural harbour and seems to have been the main settlement in Roman times. It is possible that a whole village is buried under the sand at Longis. Roman graves called ‘cists’ were found eroding out of the sand-dunes on the top of the beach before the Germans built their sea wall. Roman roof tile is also found on the beach. It is possible that the Channel Islands were governed from the Roman town of Constantia (modern Coutances).

A Roman small fort was built at the Nunnery to guard the harbour at Longis. The fort was probably built in the middle of the fourth century, but there may have been an earlier building on the same site. It is the best surviving small fort in Britain, with the walls still standing up to 5m high. It is approximately 40 metres square with walls up to 2m thick. It has rounded corners with semi-circular bastions that may have been designed to carry bolt-shooting catapults (ballistae). Originally it had a massive square tower in the centre, with walls 2.8 metres thick.

The Nunnery was probably a base for the Roman navy, which would have mounted patrols against pirates and raiders to stop them sailing through the Race. It was built at a dangerous time for Rome when ‘barbarian’ tribes were attacking from the direction of Germany and the North Sea. The Romans used small fast warships called ‘picti’ which were painted blue to hide them while hunting pirates. The Nunnery also stopped the pirates themselves using Alderney as their base. The Nunnery would have come under the command of a Roman general known as the Duke of Armorica (dux tractusArmoricanietNervicani).


In AD410 the Romans abandoned Britain and in AD 486 the Franks defeated the Roman armies and took control of Gaul. We do not know exactly when, but at some time between AD400 and AD500, Alderney ceased to be controlled by Rome.