As she raced to engage the enemy after their bold raid on Great Yarmouth, HMS D5 struck a mine left by the fleeing German vessels.

Eastern Daily Press: A survey of HMS D5, sunk off Lowestoft, has been carried out. Picture: Wessex Archaeology © Historic England/Crown CopyrightA survey of HMS D5, sunk off Lowestoft, has been carried out. Picture: Wessex Archaeology © Historic England/Crown Copyright (Image: Archant)

Fatally damaged, the submarine went to the bottom. Of her crew of 25, just five survived.

Now, just over a century on, her shipwreck – just off the East Anglian coast – is giving up her secrets.

Divers from Wessex Archaeology, working on behalf of Historic England, have been carrying out searches of the vessel and surrounding seabed, as part of a national project to locate, chart and research submarines lost in UK waters during the First World War.

The study covers 44 German and three British vessels. Of these, underwater research is being conducted on just 11 shipwrecks, because of the heightened historic significance, with D5 the only British vessel.

Eastern Daily Press: A survey of HMS D5, sunk off Lowestoft, has been carried out. Picture: Wessex Archaeology © Historic England/Crown CopyrightA survey of HMS D5, sunk off Lowestoft, has been carried out. Picture: Wessex Archaeology © Historic England/Crown Copyright (Image: Archant)

HMS D5 – the only one of its kind lost in English waters – sank just three months into the conflict, on November 3, 1914, as she headed out to sea in pursuit of the German fleet which had bombarded Yarmouth.

Mark Dunkley, maritime designation adviser for Historic England, said: 'The loss of the D5 is extremely poignant given that four-fifths of the crew perished trying to defend England's east coast from German attack.

'Historic England recognises the historical and archaeological importance of the submarine and has recommended appropriate protection to ensure that future generations continue to understand the crucial role that submarines played during the First World War.'

The site is not currently covered by the Protection of Wrecks Act 1973 – for vessels of historical, archaeological or artistic importance – and following the research, that will not change.

This is because much of the stern of the vessel is buried on the seabed, frustrating further research, while her conning tower, derrick and radio masts are also lost.

However, the report has been passed on the Ministry of Defence, and the site may be added to those covered by the Protection of Military Remains Act 1986. The researchers believe the remains of the crew are likely still on board.

Have you got a heritage story? Email mark.boggis@archant.co.uk