To put it simply, it wasn’t a war-winning weapon. Worse for Germany, it didn’t really do anything … and arguably hastened the Third Reich’s defeat. For one, the submarines—only two were ever operational—suffered from several technical problems that forced engineers to work overtime to resolve. The hydraulic torpedo loading systems didn’t work at first. The engines and steering systems were defective. This made the submarines “decidedly less of a threat than originally foreseen,” Jones writes.
On May 4, 1945 one of the most advanced submarines in the world crept up to a British Royal Navy cruiser. U-2511 was one of Germany’s new Type XXI-class “wonder” submarines, and she was hunting for Allied ships.
She also represented one of the Third Reich’s biggest failures.
More than 250 feet long and displacing 1,620 tons, the Type XXI packed six hydraulically-reloaded torpedo tubes capable of firing more than 23 stored torpedoes. This arsenal could turn a convoy into sinking, burning wreckage.
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But the real improvement lay deep inside the U-boat’s bowels. There rested an advanced electric-drive engine that allowed the submersible to travel underwater at significantly higher speeds—and for longer periods—than any submarine that came before.
It was perhaps the world’s first truly modern undersea warship. The engine, which was radical for its time, allowed the boat to operate primarily submerged. This is in contrast to other war-era submersibles, which operated mainly on the surface and dived for short periods to attack or escape.
But for the fortunate crew of that British cruiser, the war in Europe had just ended. Adolf Hitler shot himself on April 30. Word of the European ceasefire had also just reached U-2511. The submarine did not fire its torpedoes at the cruiser, instead merely carrying out a mock practice attack.
Neither U-2511 nor its sister ship U-3008 ever fired a torpedo in anger during the war. But the Kriegsmarine—the Nazi navy—had put its hopes in winning the naval war on these Type XXI U-boats.
What went wrong, and the lessons learned from the submarine program, is also the subject of new research. It was featured in Adam Tooze’s 2006 book The Wages of Destruction: The Making and Breaking of the Nazi German Economy as an example of what not to do.
Now in a recent article for the quarterly Naval War College Review, Marcus Jones—an associate professor at the U.S. Naval Academy—describes the submarine as one of the preeminent examples of Germany’s “irrational faith in technology to prevail in operationally or strategically complex and desperate situations.”
Desperation fuels innovation
The Type XXI project dates to 1943. Germany was well into a submarine war in the Atlantic, and aimed to choke and starve the United Kingdom from its colonies.
Germany’s goal was to surround the British isles with hundreds of submarines, preventing anything from getting in or out. Initially, this was successful. In October 1942 alone, U-boats sank 56 ships … and that was just in the passage between Iceland and Greenland.
But these successes turned badly against Germany—and fast. By 1943, new convoy tactics, radar and anti-submarine patrol planes caused serious problems with Germany’s predominantly Type VII submarines.
Germany’s existing submarines were now vulnerable to being detected and sunk in huge numbers. Their electric engines—used when underwater and recharged with diesel on the surface—were not capable of holding a charge lasting more than a few hours.
And they were slow. Really slow. Many convoys could simply outrun them. If the Allies detected a sub lurking underwater, they could simply wait it out. In May 1943 alone, the Allies destroyed 43 U-boats, or 25 percent of Germany’s entire operational submarine strength.
At this point, Hitler and Germany’s senior military commanders realized that “no amount of willpower or doctrinal ingenuity on the basis of existing boat types could overcome the collective effects of the countermeasures the Allies employed so well by 1943,” Jones writes.
The result was building a new kind of submarine that—in theory—would fundamentally change the nature of the war at sea.
Designed by propulsion engineer Helmuth Walter, the Type XXI had a unique figure-eight interior which allowed for a significantly larger electric battery. It only had to surface rarely surface and recharge its battery with conventional diesel fuel.
It was also fast enough to keep up with convoys. It could run silent for 60 hours at five knots. It could also pick up the pace, traveling for an hour and a half at a breakneck speed of 18 knots. By contrast the Type VII could not travel faster than eight knots underwater—and then only for short periods.