On course for Ireland, the UC-30 sails from Heligoland through the English Channel. It slips between minefields under the threat of the British.
The torpedo hits its target. It is the fourth ship Stenzler sends to the bottom as captain of the UC-30 And this is far larger than the others.
But as Hunstanton goes to the bottom and the crew of the merchant ship brought to safety, the machinery in the 40 metre, 400 tonne submarine begins to fail.
One diesel engine is completely out of function, and there are also problems with the other. There is nothing for it but to return to base at Heligoland.
Anything else could be fatal.
On 14 April 1917 the UC-30 has made it north of the little island of North Rona, not far from the Shetland Islands north of Scotland.
The UC-30 has been at sea for nearly three weeks now.
In the three weeks it has not been possible for either Heinrich Stenzler or the crew to have a bath.
Baths are not a luxury to be enjoyed on a submarine, and as the weeks pass, the air becomes a rank mixture of sweat, diesel, cooking odours and stuffiness. But no one in the crew pays any attention to this. They all smell the same.
The aisles in the UC-30 are narrow, the ceiling is low, and the constant noise from the diesel engines form the background music to life aboard the UC-30 But just like the smell, the noise becomes an unremarkable part of everyday life.
The submarine war between Britain and Germany lasted until the end of the First World War in November 1918, when the Central Powers headed by the German Empire, surrendered.
During the war Germany produced 375 submarines. 178 of them were lost at sea and with them 5,000 men. The British, however, lost 5,000 ships to sea mines and submarine attack. Here, the vast majority were merchant ships.
Despite the fact that Denmark was neutral during the war, 305 Danish ships went to the bottom and more than 700 sailors lost their lives - partly because of German and British mines in the trade routes between Denmark and England.
Research: Simon Leth Stolzenbach, DR Arkiv
Graphics og animation: Morten Fogde Christensen
Video: Dennis Normann
Topvideo: Zangs Films / Shutterstock
Webdok editor: Hans Christian Kromann
Sources: The reconstruction of UC-30's last mission is build on old letters, logbooks, articles and interviews with Søren Nørby, Institute for Military History and War Studies at the Royal Danish Defence College , Poul Grooss, former naval officer and military historian at the Royal Danish Defence College and Gert Normann Andersen, Sea War Museum.
'British Merchant Ships Sunk by U-boats in World War One' by A. J. Tennent,
'From Imperial Splendour to Internment: The German Navy in the First World War' by Nicolas Wolz,
'U-boat Hunters: Code Breakers, Divers and the Defeat of the U-boats, 1914-1918' by Robert M. Grant,
'Dansk vejr siden 1874' by John Cappelen and Bent Vraae Jørgensen.
Websites: Uboat.net, Wrecksite.eu, Onlineproject Gefallenendenkmäler.
Published: August 18th, 2016.