The Desperate Origins of Germany’s U-Boat Campaign

When World War II began in September 1939, Germany’s Kriegsmarine found itself severely outmatched by the British Royal Navy. Grand Admiral Erich Raeder, commander of Germany’s naval forces, faced a grim reality – his surface fleet stood little chance against Britain’s naval supremacy. This imbalance forced Germany to rely increasingly on its U-boat (submarine) fleet as its primary naval weapon.

The architect of Germany’s U-boat strategy was Karl Dönitz, a veteran U-boat commander from World War I who had spent years developing revolutionary submarine tactics. Dönitz understood that Germany’s limited number of U-boats (only 22 were operational for Atlantic operations at the war’s outset) needed to be used with maximum efficiency against Britain’s vulnerable merchant shipping lanes.

Early successes seemed promising. From September to December 1939, German U-boats sank 114 Allied merchant ships. The U-48 under Captain Herbert Schultze became the first U-boat to sink over 100,000 tons of shipping, earning Schultze the Knight’s Cross. These early victories, however, masked significant problems with Germany’s submarine warfare capabilities.

The “Lone Wolf” Phase and Its Limitations

Initially, German U-boats operated independently as “lone wolves,” patrolling assigned sectors of the Atlantic. This approach had some success but proved inefficient. The vastness of the ocean meant submarines often failed to locate convoys, and when they did, single U-boats struggled against convoy escorts.

A dramatic example occurred when U-47, commanded by the famous Günther Prien (who had sunk the British battleship HMS Royal Oak at Scapa Flow), encountered a British convoy off Norway. Despite perfect positioning, U-47’s torpedoes failed to detonate – a recurring technical problem that plagued German submarines early in the war. Prien barely escaped the subsequent depth charge attack, writing in his log: “Wooden guns would be just as useful in war.”

The psychological toll on crews was severe. After three torpedoes failed to detonate against the battleship HMS Nelson, U-56’s captain, Wilhelm Zahn, suffered a nervous breakdown and was relieved of command. These incidents revealed critical flaws in German torpedo detonators – both magnetic and contact types were unreliable, sometimes passing harmlessly beneath targets or failing to explode on impact.

The Norwegian Campaign Debacle

In April 1940, Hitler ordered U-boats to support the invasion of Norway, diverting them from commerce raiding. The campaign proved disastrous for submarine operations. Thirty-one U-boats made thirty-six attacks against British warships and transports without a single success, again due to faulty torpedoes.

The technical investigation that followed revealed multiple defects: magnetic detonators failed in Norway’s mineral-rich waters, contact pistols sometimes didn’t fire, and torpedoes often ran deeper than set. These problems weren’t fully resolved until mid-1940, forcing U-boats to temporarily abandon magnetic pistols.

Norway represented a strategic victory for Germany but a naval catastrophe. The Kriegsmarine lost 10 destroyers and several other vessels, leaving its surface fleet crippled. As Churchill noted, Germany had “expended her own navy” in the campaign. U-boats sank no ships while losing six of their own, dealing a severe blow to morale.

The “Happy Time” and New Tactics

France’s fall in June 1940 transformed Germany’s naval position. Access to French Atlantic ports like Lorient and St. Nazaire reduced transit times to hunting grounds by 450 miles, effectively doubling operational U-boat numbers. Dönitz established his headquarters at Lorient, perfectly positioned to coordinate attacks.

This period (July 1940-May 1941) became known as the “Happy Time” (Die Glückliche Zeit) as U-boats ravaged Allied shipping. Dönitz implemented new tactics: night surface attacks where U-boats’ low silhouettes avoided detection while targeting ships backlit against the horizon. The daring Otto Kretschmer in U-99 became particularly adept, once sinking four ships in one night.

Success bred confidence. U-47’s Prien, U-99’s Kretschmer, and others like Joachim Schepke (U-100) became national heroes. In six months, U-boats sank over 300 ships totaling 1.5 million tons. The British Admiralty seemed powerless against these attacks, especially since ASDIC (sonar) couldn’t detect surfaced submarines effectively.

The Wolf Pack Strategy Unleashed

Despite successes, Dönitz recognized single U-boat attacks had limitations. Drawing from his World War I experience (he’d been captured after a failed solo attack), he developed the Rudeltaktik (“pack tactic”), soon nicknamed “wolf packs” by Allies.

The concept was simple but devastating:
1. U-boats spread across probable convoy routes
2. First submarine to spot a convoy shadowed while radioing headquarters
3. Dönitz coordinated other U-boats to converge
4. Attacks occurred simultaneously at night from multiple directions, overwhelming escorts

In October 1940, the first true wolf pack attack occurred against convoy SC-7. Seven U-boats sank 20 of 30 ships. Days later, another pack attacked HX-79, sinking 12 more. The tactic proved terrifyingly effective – in 1940 alone, U-boats sank 471 ships (2.2 million tons).

The Tide Turns Against the Wolves

Several factors eventually countered the wolf packs:
1. Britain’s convoy system expanded and improved
2. Radar-equipped aircraft closed the “Atlantic Gap”
3. High-frequency direction finding (HF/DF) located shadowing U-boats
4. More escort carriers and destroyer escorts entered service
5. Breaking German naval codes (Ultra intelligence)

By mid-1941, losses mounted. Kretschmer was captured (March), Prien killed (March), and Schepke killed (March). Improved Allied tactics and technology gradually reversed the tide. May 1943 became known as “Black May” when 41 U-boats were lost, forcing Dönitz to withdraw from the North Atlantic.

Legacy of the U-Boat Campaign

Germany’s U-boats sank over 2,800 Allied ships (14 million tons) during WWII, but at horrific cost – 785 U-boats lost (75% of crews). The campaign demonstrated:
– The strategic importance of submarine warfare
– How technological innovation constantly shifts naval advantage
– The critical role of intelligence in modern warfare
– That ultimately, industrial production (like Liberty ships) could outweigh tactical successes

Dönitz’s wolf pack tactics revolutionized naval warfare, influencing submarine strategies into the Cold War. Though ultimately unsuccessful in cutting Britain’s lifelines, the U-boat campaign remains one of history’s most dramatic naval conflicts, pitting courageous crews against impossible odds in the Atlantic’s unforgiving depths.