Hitler’s greatest mistake might’ve been a U-boat purchase refusal

The U-boats and their wolf packs were a major threat in World War II, even though they were few in number. A German admiral wanted 300.
Logan Nye Avatar
donitz u-boat
Dönitz observing the arrival of U-94 at St Nazaire in France in June 1941.

If you had to decide what the stupidest thing Hitler did was, what would you pick? Besides, you know, being a racist fascist? The invasion of the Soviet Union is a good option, as is the subsequent abandonment of Moscow to split his forces against Stalingrad and the oil fields. Taking on Italian failures in North Africa and committing needed resources there is also solid. The use of amphetamines and encouraging its use by his troops? The fascination with wonder weapons?

All solid, defendable choices. But I have an impactful and easily overlooked alternative: A failure to properly fund his U-boat fleet, the actual wonder weapon that worked, had a good record, and could have knocked Britain and its empire out of the war. If he had just signed off on the one, admittedly very large, purchase order of U-boats from Admiral Karl Donitz, he might’ve won.

The importance of the U-boats

Hitler’s initial plans for Europe were ambitious and evil but rational. He wanted to push west, punish France for its victory in World War I, conquer territory, and keep Great Britain from joining the war before turning east. But Britain, alongside France immediately joined the conflict as Germany invaded Poland.

The original plan for the German navy, the Kriegsmarine, had been to build up its surface fleet strength over years before fighting Great Britain. Instead, at least on paper, it was at war with the world’s largest navy and merchant fleet. But the British fleet was old and undermaintained.

Dönitz as Grand Admiral in 1943.

This gave an opening for the Germans to lean into their most important naval weapon: the U-boat. On early patrols, these boats inflicted stunning losses with the average U-boat sinking four Allied ships per patrol. On rare occasions, this was a British warship. But the boats really targeted shipping, starving out the British leadership.

The German plan

Grand Admiral Karl Donitz was a well-respected navy officer who would briefly serve as the head of the German state after Hitler’s suicide in 1945. But in 1939, he was just one of the many senior officers courting Hitler for limited state resources to prosecute the war. Steel was in especially short supply as Germany was bad at making the high-quality stuff and the army needed it for tanks, the navy for surface ships, and the air force for plane engines and parts.

And Donitz wasn’t the lead admiral speaking in Hitler’s ear. That was Grand Admiral Erich Raeder. Raeder firmly focused on surface fleets, creating Plan Zebra to expand Germany’s navy, largely through constructing aircraft carriers, new battleships, and cruisers. Raeder had limited respect for submarines and Hitler, at the start of the war, had even less.

Donitz wanted to take the war to the British fleet and sink 600,000 tons per month. To do so, he asked for 300 U-boats. Instead, he he started the war 43 and had just 57 when Britain joined. When he was careful and saved up, Donitz could get 30 of them into the water at once, but sometimes had as few as 12 on patrol as the rest underwent maintenance or were in transit.

The U-boat threat

Despite the tiny size of the fleet, Donitz quickly proved the effectiveness of the crews and weapons. The U-boats claimed 70% of the ships sunk by the Navy. It quickly crippled British commerce, killed half of the sailors it forced into the North Atlantic, and forced the overstretched British fleet to dedicate resources to convoy escort.

In May 1940, U-boats sank 55,580 tons of shipping. But in October, they sank 352,407. Despite the tiny fleet size, they were well on their way to reaching Donitz’s goal of 600,000 tons. In late 1941, U-boats sank the British carrier HMS Ark Royal and the battleship HMS Barham.

uss barham sunk by u-boat
USS Barham underway at low speed, mid-1930s.

Indeed, after the successes of 1939-1941, Donitz even sent his U-boats across the Atlantic to attack the U.S. on its East Coast, in the Caribbean, and in the Gulf of Mexico.

And Hitler eventually took notice. In 1941, Germany expanded its U-boat construction and Donitz could keep 36 boats on patrol. It was a terrifying time for Allied sailors and merchant marines.

Meanwhile, for all the talk of British success cracking the Enigma codes, Germany actually had great cryptological hygiene compared to the Allies and its own crack unit for breaking enemy encryption. The U-boats often had a great idea of where convoys were, hunted in packs, and threatened Britain with collapse. In the first months of 1942, sinkings skyrocket and Germany averages almost 900,000 tons per month, 50% higher than Donitz’s plans.

So, what went wrong?

The hunting of the wolf packs

Hitler waited too long to see the value of the U-boats, the wolf packs, and Donitz’s plans. By the time Germany expanded U-boat construction, Britain had already smuggled radar and sonar to America to the devices mass-produced. And code crackers slowly figured out how to decode U-boat messages.

Soon, submarines found themselves unable to find targets. And when Allied warships find them, the U-boats find it harder to hide as sonar and radar operators pin them down.

A slow tipping of the balance in late 1942 became a complete reversal in 1943. Royal Navy divers captured new Enigma codebooks that allowed code crackers to figure out the new codes. The U.S. Navy joined in the hunt of wolf packs. New planes with longer ranges allow for more effective bombing of the submarines. And new weapons like the hedgehog allow ships to quickly attack entire sections of the water at a time.

May 1943 became “Black May” for the U-boats. On May 24, as staggering losses piled up, Donitz pulled the boats from patrol. In June 1943, every convoy made it across the Atlantic in relative safety. For the rest of the war, German U-boats were on the back foot and struggled to survive, let alone find ample targets.

We’re very lucky they’re so stupid

It’s easy to imagine that with a greater emphasis on U-boat warfare earlier, before the U.S. joined the war and the proliferation of sonar and radar, Germany might have successfully starved Great Britain out. If Donitz’s plans had been embraced, he might have had six times as many U-boats.

Britain failing would have let Germany focus more resources east for its invasion of the Soviet Union, potentially even letting it successfully digest the oil fields there. And American convoys to the Soviet Union would likely have failed with Britain out of the war and more subs in the water.

The task for freedom-loving people around the world would’ve been nearly unattainable. So we’re all very lucky that they, the Germans, were so stupid.