Divers have now been able to film the pioneering vessel which helped Britain to naval victory in the First World War
British divers and a US–based naval historian have succeeded in discovering the world’s first truly modern submarine – at the bottom of the English Channel three miles off the coast of Devon.
Built 112 years ago, she had much greater effective range than any other submarine that existed at that time and was more powerful than any of its competitors.
With its greater range and capability, it changed the nature of naval warfare.
Marine archaeologists and divers have known for many years that the wreck of an early submarine lay off the south Devon coast but they believed that it was a First World War German U-boat.
Now, however, after three years of research, historians and divers have concluded that the sunken vessel wasn’t German after all but was a pre-War British prototype known as D1. The wreck is of huge international importance because she was the world’s first genuinely offensive, rather than purely defensive, submarine.
Her cruising range of 2,000 nautical miles (50 per cent greater than any other British submarine at the time of her commissioning) and her greater manoeuvrability, speed, size and power temporarily gave Britain a significant naval advantage.
But D1 was also part of an arms race in which the Germans launched the U5, almost as technically advanced, less than a year after the D1 had gone into service. The newly rediscovered epic British prototype long-range submarine is of such great historical importance that, on Historic England’s advice, the government has now scheduled her as a protected historic monument.
D1 was able to remain at sea for at least a week and was therefore able to hunt down enemy warships, rather than merely defending Britain’s ports, as her less-robust predecessors had done.
She was six metres across, 50 per cent wider than previous British submarines. Her width gave her increased buoyancy and stability and made her much more robust and seaworthy.
Crucially, she was the world’s first long-range submarine to be diesel-powered, rather than petrol-or-paraffin-powered – and that made her much safer, with a massively reduced risk of explosion and fire.
What’s more, she had two propellers, which helped give her an ability to change direction much more rapidly.
And last but not least, she was the first royal navy submarine able to fire torpedoes from her bow and her stern – which gave her and the other D class submarines, which were built after her, an ability to attack enemy vessels without having to turn through 180°.
D1 completely changed the navy top brass’s attitude to submarines. In large–scale wargame manoeuvres in 1910, she was so successful that she utterly transformed naval thinking.
Her performance, “opened the eyes of the first sea lord, Admiral Sir Arthur Wilson, to the offensive possibilities of submarines, which he had hitherto regarded as defensive vessels”, wrote Commodore Roger Keyes, who was head of the navy’s submarine service between 1912 and 1915.