Keynvor Morlift, in conjunction with Bournemouth University’s Dr Innes McCartney, have identified the remains of the WW1-era German U-boat ‘UC66’, 15 nautical miles north of the Isles of Scilly.

The discovery reveals that ‘UC66’ was the first submarine in history to be sunk by an aircraft attack when it was bombed off the Scillies on 27 May 1917.

The U-boat had made an attack on a British ship, ‘HMS Acton’, and the gunfire was heard at the seaplane base at Tresco. A seaplane was scrambled to investigate and found a U-boat running on the surface, and under a hail of machine-gun fire, dived to attack. The plane dropped four 100lb bombs and the submarine was then seen to sink by the bow.

The pilot’s report stated that the U-boat had a “high fo’c’sle” (the UCII-Class minelayers had a high forward section where the mine chutes were located), and that the plane was hit by several bullets. One penetrated the starboard side radiator, and the leak was only staunched by engineer CPO Tadman climbing out onto the wing and holding a towel over the hole until the plane landed. All four of the plane’s crew received medals.

The identification of the wreck was made using KML’s vessel ‘Severn Sea’ using her on-board Cougar-XT ROV. The submarine was found to be lying on its side and to be broken in half.

Dr McCartney said: “All the features of this wreck site confirm it is a UCII minelayer. The only one to have been lost at the time of the air attack is ‘UC66’ and the location of the wreck is close to where the bombing took place, confirming the wreck’s identity. It had been only a theory that ‘UC66’ would be found here.”

“In 1919 when the Royal Navy drew up the official list of U-boats destroyed it listed ‘UC66’s destruction to another incident, involving a depth-charge attack off Lizard Point. The record will now need to be corrected to show that this was the first successful air attack in history against a submarine. I am very grateful to Keynvor Morlift for working with me on this exciting discovery.

There are 63 German U-boat wrecks in the English Channel. ‘UC66’ is one of the last to be positively identified by archaeologists.

Sacha, skipper of the Severn Sea said, “KML and the crew of the Severn Sea are extremely proud to have played a part in helping to locate and identify the wreck of UC66. Conditions on site were ideal for the search and subsequent survey.”

“The agility of the ROV allowed a close inspection of the wreck, gaining valuable information and enabling a positive identification. Working around subsea hazards and marine debris is where the Cougar-XT comes into its own, proving invaluable in achieving extended operating times at depth.”

“Dr McCartney’s passion and knowledge for his subject was infectious, giving the crew a glimpse of a valuable piece of maritime and war history and treating the site with the respect it deserved.”