A Century After This WWI Sub Sank, Experts Finally Solved The Mystery Of Its Top-Secret Cargo

More than a century later, Dr. Rodrigo Pacheco-Ruiz of England’s University of Southampton leads an expedition to explore the wreck of the long-lost submarine. The stricken sub lies 150 feet deep but a team of hydrographic surveyors and maritime archaeologists score a notable first. They capture the first images of the German submarine UC-47 ever seen since it slipped beneath the waves in 1917.

The experts actually used two underwater robots to survey the rusting remains of the sunken submarine. This allowed them to take video footage of the wreck and to create stunning three-dimensional images using advanced echo-location devices. Now we can all view astonishing images of UC-47 in her final resting place deep below the surface of the North Sea. 

Dr. Pacheco-Ruiz and his team hoped that their exploration of the wreck would help to solve a 103-year-old mystery. After the submarine sank, according to some accounts British naval authorities made determined efforts to salvage something from the wreck. The German military authorities certainly seemed to have believed that the British found something: an item of extremely high value.

But just what was it that the Royal Navy was so anxious to retrieve? Dr. Pacheco-Ruiz and his experts believed they might be able to solve the puzzle. In a press release from the university’s Centre for Maritime Archaeology, the team leader described the work that went into their survey of the UC-47 wreck.

Dr. Pacheco-Ruiz said, “Today the vessel is only marked on the navigation charts as a shipwreck and until now very little was known of the submarine’s condition. It has been a privilege to be able to explore a wreck in such good condition and have the opportunity to find out more about its past.” And that’s obviously the most intriguing element. Just what did happen when UC-47 sank – and in the days afterwards? What was it, exactly, that the British sought so keenly?

To get to the bottom of this mystery, we first need to understand the story of that German submarine UC-47. For starters, what she was doing in the North Sea off Britain’s Yorkshire coast in November 1917? Well, during World War I, the Germans built and maintained a large fleet of submarines. They used them to sink as much merchant and naval shipping as they could, a strategy the first started employing in the first few months of 1915. The Germans hoped to force the British into surrender for want of essential supplies.

But the Germans called a sudden halt to their program of submarine warfare in late 1915. The reason? It was the sinking of the R.M.S. Lusitania in May 1915. This was a passenger liner and she was hit by a U-boat’s torpedoes as she sailed towards the English port of Liverpool from New York.The ship sank in just 20 minutes with the loss of 1,195 lives.

Crucially, 128 of those casualties were U.S. citizens. America, at that point not a participant in WWI, was outraged. President Woodrow Wilson threatened the Germans with retaliation and the latter decided to call a halt to their aggressive submarine attack policy. But this enforced restraint was not to last. It came to an end in January 1917. 

From then Germany’s submarines again began to take a deadly toll on British shipping and other vessels bound for the country. And that is exactly the mission in which UC-47 was engaged when a British patrol boat encountered her in the North Sea in November 2017. In fact, the submarine had only been launched from the A.G. Weser shipyard at Bremen in Germany’s north-west in August 1916.

UC-47 had then been commissioned into active service in the following October. So by the time she was sunk in 1917, she’d only been on active operations for 13 months. But they had been a very busy – and lethal – 13 months. As we’ve seen, the Germans had returned to unrestricted submarine warfare in January 1917 and UC-47, skippered by Kapitänleutnant Paul Hundius, took full advantage of this freedom to attack and destroy.

From January 31 until the beginning of October 1917, Hundius and his crew succeeded in sinking more than 50 ships. Steamers, fishing smacks, sailing vessels, Navy trawlers and even one British destroyer went to the bottom of the sea thanks to the efforts of UC-47. Most of the destroyed shipping had sailed under the British flag but there was also the odd Greek, French, Italian and Norwegian victim. 

Kapitänleutnant Hundius’ reign of terror aboard UC-47 came to an end in early October 1917 and soon after Oberleutnant Günther Wigankow took over as the submarine’s captain. When he assumed the captaincy Wigankow had every intention of carrying on from where his predecessor had left off. After taking command on October 9, just nine days later Wigankow and his crew sank two British steamers.

During the first half of November, UC-47 went on to sink three more steamers, two British and one French, and a Netherlands-flagged fishing boat. But that Dutch sailing vessel, sunk on November 12, would be the last of UC-47’s victims. Just days later Oberleutnant Wigankow and his men met their nemesis off the coast of the northern English county of Yorkshire. 

Apparently UC-47 had been considered by many German Navy sailors to be a “lucky” boat. Up until dawn on November 18, 1917, that was true enough. But on that day, off a spit of land called Flamborough Head on the Yorkshire coast, she crossed paths with H.M.S. P-57, a British Royal Navy patrol boat. UC-57 had set sail from the Belgian port of Zeebrugge the day before with orders to destroy enemy shipping off England’s east coast.

P-57 was captained by Lieutenant-Commander Harry Birnie of the Royal Naval Reserve. In fact, he’d only taken command of the patrol boat on October 23, just a week after Wigankow took the captaincy of UC-47. P-57 had been launched from the William Hamilton & Company shipyard in Port Glasgow, Scotland, in August 1917.

Patrol boat P-57 was part of a 60-strong fleet specially fitted-out to counter the German U-boat menace. She had a low profile in the water which would have made it harder for a German commander to spot her through his periscope. Her prow was strengthened with hardened steel so that she could ram enemy craft. And she sported a four-inch cannon. 

Finally, she was equipped to use depth charges, a highly effective method of bombing submarines out of the water. These explosive devices had been developed by the British during WWI. So this patrol boat was a formidable opponent indeed for any German submarine that she happened to come across. UC-47 found herself in that unenviable position.

It was early on the morning of November 18 when P-57 came across the U-boat UC-47 sitting on the surface. Researchers have wondered why the submarine should have been in this vulnerable position. After all she was only a little more than 20 miles from the English coast in an area where patrol boats were quite likely to be out.

A local team led by a diver called Shaun Carr might well have solved that puzzle in 1997. They dived down to the wreck that year and one of the things they noted was that the submarine’s radio mast was fully extended. So it’s quite possible that the German boat was trying to make radio contact with her home base of Bruges in Belgium.

The first light of day had not quite appeared in the sky when a lookout aboard P-57 alerted his skipper to what he thought was a buoy floating in the sea. Lieutenant-Commander Birnie was baffled because his charts recorded no buoy in this location. He changed course to get a closer look at the unexplained object in the water. 

It quickly became apparent that this was no buoy. It was the conning tower of a submarine and it was just 200 yards away. Birnie barked out his orders and P-57 veered to port, its engines immediately gunned to top speed. It took a mere 15 seconds for the patrol boat to home in on its target. At this point the submarine didn’t have a chance.

The patrol boat smashed into the submarine’s side, ripping a hole in UC-47’s hull. The impact forced the sub below the surface and off to the stern of the British vessel. But that wasn’t the end of the attack: far from it. Now Birnie ordered his crew to unleash a depth charge. Then P-57 made a sharp about-turn and sailed back over the spot where the submarine had submerged. Birnie took the opportunity to drop a second depth charge.

Even then, the British patrol boat’s attack on the German submarine was not over. For the moment though, Birnie marked the spot where the U-boat had disappeared and simply bided his time. After a short wait, oil began to bubble up to the sea’s surface. Birnie promptly launched another depth charge at the spot where the fuel was emerging. 

Birnie marked the spot where he’d dropped that last depth charge and remained at the site for the remainder of the day and the next night. No survivors from the submarine were sighted. It was apparent that all 28 of UC-47’s crew had perished in the engagement. That was made all the more definite when a minesweeper arrived on the scene and caught the submarine in drag-chains lowered to the sea-bed. The chains had an explosive attached which was duly detonated.

According to an August 2020 account of the engagement in The Independent newspaper, P-57 dropped yet another depth charge onto the stricken German submarine in the afternoon of the day after she’d rammed the U-boat. The patrol boat stayed on the scene for nearly three days and reported that air bubbles continued to erupt from the sea’s surface. 

The Independent continued its account by saying that the patrol boat carried on dropping depth charges on the already sunken submarine. It did this because it was impossible to gain entry to the vessel stuck 150 feet below the surface. But there was something in the German boat that the British badly wanted. 

Smithsonian magazine in a report from August 2020 pointed out that the British may have continued to depth-charge UC-47 in an effort to force documents to the surface though the impact of the explosions. Just what papers had UC-47 been carrying that the British were so keen to recover?

These secret German papers may have included code books and charts: they were the treasure that the British were hunting. You see, these charts would have detailed the positions of mines laid around the British coast. These minefields could be just as deadly to British naval and merchant shipping as the attacks of the U-boats. Indeed, the Library of Congress website notes that German mines sank about 500 merchant vessels as well as nearly 270 Royal Navy ships.

But here the mystery deepens. Could the British really only retrieve these vital documents by exploding depth charges over UC-47’s sunken hull.? In fact some accounts state that the British did actually get a diver down to the wreck. Stephen Fisher, a maritime historian, mentions this theory in the University of Southampton release about the 2020 expedition to UC-47.

Fisher said, “The day after her loss, UC-47 is reputed to have been visited by Royal Navy divers who retrieved valuable intelligence, including code books and charts. Further investigation of historical sources – when access becomes available as lockdown eases – combined with this detailed imagery of the wreck, might enable us to ascertain if she was indeed visited in November 1917.” 

But the Smithsonian, in its August 2020 report of the recent exploration and survey of UC-47, casts doubt on the story that a diver or divers actually made it down to the wreck in 1917. It says that 150 feet would likely have been too deep for the diving technology available at the time. All the same, another source is in no doubt that there was a dive down to the submarine soon after it sunk.

In his 2003 book The Tin Openers, British author and diver Kendall McDonald described the 1917 dive down to UC-47. He wrote that a Royal Navy diver called Dusty Miller, wearing the hard helmet used by divers of the day, entered the U-boat via its conning tower hatch. Reaching the control room he retrieved a metal box that contained codes, logs and the vital charts of two minefields. 

Further evidence that Miller may have descended down to the wreck despite its depth comes from an account of Shaun Carr’s 1993 UC-47 dive we mentioned earlier. Carr noted that when he explored the U-boat, the conning tower hatch was still open as Miller had apparently left it. This meant the control room Miller is said to have entered was now clogged up with silt. 

Certainly the Royal Navy diver Warrant Shipwright Ernest Charles “Dusty” Miller did exist and was active in salvage operations during WWI. And the Proceedings of the 24th Annual Diving Conference of 2014 reports a dive Miller made in 1918 to a submarine off Cornwall at a depth of 21 fathoms. That’s 126 feet, not far off the 150 feet of water in which UC-47 lies.

The Independent article pointed out that researchers have uncovered no official records of crucial intelligence being retrieved from UC-47. But it seems that high-level German naval intelligence officers believed that British divers had seized key documents. Perhaps close scrutiny of German wartime archives may one day conclusively reveal the truth.

What we’re left with is the undeniably spectacular images of UC-47 that Dr. Pacheco-Ruiz and his team captured in 2020. So 103 years after a British patrol boat’s reinforced steel prow smashed into UC-47, we can see the results for ourselves. The three-dimensional images created with high-tech scanning equipment are particularly stunning. 

Considering its age, the stricken German U-boat – which is of course a war grave for the 28 submariners who lost their lives – is in remarkably good condition. The entire length of the hull is preserved and the damage inflicted on her by P-57, including a gaping hole, is clearly visible. One of the torpedo tubes, separated from the vessel, lies nearby.

And finally we can be fairly certain that we now know the true nature of that valuable cargo the British were so anxious to obtain. Invaluable intelligence about the whereabouts of minefields was stowed in the submarine’s control room. Armed with the knowledge those charts held, it’s highly likely that the Royal Navy would have been able to save many ships from sinking. 

So it’s just possible that the efforts to retrieve those secret documents from the sunken hull of UC-47 could have had a material impact on the outcome of the war. After all, if the German submarines and minefields had succeeded in blockading the British during WWI, 20th century Europe might have become a very different place.