Cutting Off Commerce: How U-Boats Strangled American Supply Efforts

June 14, 2021 Topic: History Blog Brand: The Reboot Tags: World War IIU-boatsNazi GermanyU.S. NavySupply

Cutting Off Commerce: How U-Boats Strangled American Supply Efforts

Operation Drumbeat did see success for the Germans...initially.

Key Point: It took a herculean effort by the admiral to scrounge and prepare enough U-boats to make an impression.

On December 9, 1941, Grand Admiral Erich Raeder, the commander of the Kriegsmarine, lifted all restrictions on German naval attacks against American vessels by his surface and submarine fleets. Atlantic sparring between the two powers had been occurring for several months but would now escalate into full-blown conflagration. For the United States a painful lesson on the consequences of complacency and arrogant refusal to accept outside assistance was coming.

Despite their fearsome reputation, the U-boats commanded by Admiral Karl Dönitz were few in number. When war flared with Great Britain on September 3, 1939, he counted just 57 U-boats, 46 of which were operational. German industry had concentrated on armaments to prosecute a war on land and in the air, and the deliveries of new submarines to the Kriegsmarine amounted to a paltry two per month. Despite this scarcity, ongoing mechanical problems, and unreliable torpedoes, Dönitz’s crews sank over a million tons of British shipping from July through October 1940 in what the submariners called the Happy Time.

The U-boat chief estimated a fleet of 300 submersibles would be required to adequately cut England off from its outside sources of supplies, and with his minuscule fleet’s early successes he may not have been overly ambitious in proclaiming that he might knock Great Britain out of the war before the United States entered the conflict. His hopes rose along with production figures, which later increased to 20 U-boats per month by the time Germany declared war on the United States in December 1941. It was time to show the Americans what they could expect from their adversaries and perhaps even make them think twice about dispatching an expeditionary force to Europe.

If the U-boats could seriously disrupt Atlantic shipping and also sink American supply ships close to their own shores, the losses would be even more demoralizing. Dönitz commenced plans for his first hunting forays into U.S. coastal waters. He called the missions Operation Drumbeat.

Dönitz the Lion

It took a herculean effort by the admiral to scrounge and prepare enough U-boats to make an impression. In December he possessed just 91 operational submarines. Twenty-three were in the Mediterranean, three were en route there, six were stationed just west of Gibraltar, and four were off Reykjavik, Iceland. Thirty-three of the remaining 55 were dry-docked for repairs and maintenance. Eleven more were embarking for or returning from patrols, six were undergoing refit, and five were in the middle of patrols.

Hoping to utilize the long-range Type IXB and IXC boats, Dönitz implored the high command for 12 more IXBs. He managed to get six.

Dönitz’s men called him the Lion. He demanded perfection from his sailors in their confrontations with the enemy. Unsatisfactory performance was not tolerated, but the yearning of his U-boat crewmen to achieve his standards was induced by much more than fear. The Lion never failed to meticulously look after the well-being of his men, assuring that their rations, medical facilities, and overall readiness for combat were the best of the Third Reich’s branches of the military. He was invariably present on the dock at Lorient, France, as his boats embarked on and returned from their voyages, and his sailors’ fervent desire to please him ensured the success of Germany’s submarines early in World War II.

The Sickly Hardegen Takes Command

Kapitanleutnant (Lieutenant Commander) Reinhard Hardegen would play a prominent role in the coming offensive. Originally trained as a naval pilot, Hardegen’s aviation career was cut short by a plane crash in the 1930s that left him with a shortened right leg, permanently bleeding stomach lining, and lifelong diptheria. He was able to stay in his beloved Navy by having himself frequently transferred a step ahead of his medical transcript, which always arrived at his postings just after he departed. Doctors repeatedly learned of his physical debilities only after he had left their jurisdictions, but on the eve of his country’s first serious strikes against its powerful new enemy his clinical records caught up with him.

Hardegen had told Admiral Hans-Georg Friedeburg, a lieutenant of Dönitz, that he was “fit to return to the sea,” without specifically mentioning U-boats, which had little room for sickbays. When Hardegen repeated this clever wording to Dönitz,who had been grimly poring over the medical report, the admiral was impressed and amused by his fearless young commander’s desire and ambition. Despite describing Hardegen as “pale as a boat’s wake,” Dönitz had to admit this was the kind of man he needed at this time. The sickly officer was on his way to America as skipper of U-123.

After briefing Hardegen and two more of his submarine commanders, Richard Zapp of U-66 and Ernst Kals of U-130, Dönitz swiftly but efficiently guided Operation Drumbeat as it began to take shape. These three officers and their commands would make up Group Hardegen. They would steam as soon as possible for the U.S. East Coast and rendezvous with two other U-boats designated Group Bleichrodt. These five submarines would unleash an unprecedented reign of terror on the pitifully unprepared American coastline during the first six months of 1942. It was a campaign that went largely unnoticed by a German populace preoccupied with the Russian front and an American public still in shock over the Japanese attack on Pearl Harbor and anxiously watching the Philippines. It was nonetheless a monumental clash, and for the men involved it was the center of the universe.

Sailing to the American Coast

At 9:30 am on December 23, 1941, Hardegen’s U-boats, laden with everything from torpedoes to Christmas presents, weighed anchor and churned into the Bay of Biscay. The New World was far from ready for its approaching attackers. No blackouts, radio silence, or other precautions of any note were being employed, and the wolf pack would find excellent hunting.

Just before midnight on the 27th, U-123 crossed the demarcation line of 20 degrees west, where German submariners could finally learn their precise destinations. Opening their sealed orders, Hardegen assembled his officers and showed them the contents: a map of the U.S. East Coast and tourist guides to New York City. With the sudden American entry into hostilities, Dönitz had no detailed navigational material for the U.S. East Coast and was forced to send military personnel to forage through libraries to collect even this much.

Hardegen also learned from the orders that following the initial attacks off New York the U-boats were to move steadily southward, assaulting shipping until reaching Cape Hatteras, North Carolina, where their fuel would be running low, necessitating a return home.

The crew settled into a routine over the next few days as they steamed uneventfully across the Atlantic. Then, at 4 am on January 2, a wireless transmission arrived instructing Hardegen to attack a Greek freighter that had broken radio silence and broadcast a distress signal because of a damaged rudder. Guided by the ongoing directions the vessel, Dimitrios, was sending to an approaching ocean-going tug, U-123 advanced to point-blank range late on the night of the 4th, only for her crew to realize at the last second that two destroyers were escorting the Greek ship. Hurriedly backing off without being noticed, Hardegen resumed his westward trek.

Office of Naval Intelligence in Shambles

Although disgusted with himself for not having attacked, Hardegen had likely saved his U-boat. The Drumbeat boats were already being tracked by British naval intelligence. The dispatch informing him of Dimitrios’s position had been intercepted, decrypted, and passed on to the Canadian Navy, accounting for the destroyers’ presence. In fact, all five submarines were being plotted on their transatlantic passages by Royal Navy cryptanalysts at their headquarters in the town of Bletchley, 50 miles northwest of London.

Bletchley-based U-boat tracking specialist Rodger Winn was familiar with U-123 and even had Hardegen’s dossier. He knew this German was aggressive and independent and that Dönitz had recently begun pulling his U-boats from the high seas convoy routes despite heavy losses off Gibraltar. Abandoning the mid-Atlantic shipping lanes at a time when he no longer had sufficient reserves to withdraw from other theaters to replace those removed from North Atlantic convoy hunting was a baffling maneuver unless the Kriegsmarine was implementing a major strategy change.

Since Hitler had just declared war on America, it did not take Winn long to deduce Dönitz’s intentions. By telling an aide, “Be sure that the people upstairs keep Washington informed,” he made the first of Britain’s attempts to warn her powerful but ill-prepared ally of the approaching peril.

In Washington, the U.S. Office of Naval Intelligence (ONI) was in shambles. Taken totally by surprise by Pearl Harbor, it was also a jumble of unnecessarily complex administrative structures, confusion, and internal feuding. Furthermore, the director of War Plans in Operation, 55-year-old Rear Admiral Richmond Kelly Turner, looked upon counterintelligence and espionage with profound contempt and refused to utilize the ONI, whose very capable head, Captain Alan G. Kirk, had resigned in disgust in October 1941.