Military history

GERMAN NAVAL OPERATIONS

In Berlin at the start of the third year of the war, Barbarossa, the German invasion of the Soviet Union, dominated all else. Hitler personally directed the Germans from a secret hideaway, Wolfsschanze (Wolf’s Lair), in eastern Prussia. Worried about his far-flung flanks, he rejected a recommendation of his generals for a massive blitzkrieg in the center toward Moscow and strengthened the northeastward drive on Leningrad and the southeastward drive on Kiev. These diversions delayed the drive on Moscow (Operation Typhoon) to October 1, perilously close to the onset of winter.

By comparison, the Desert War in North Africa was a puny sideshow: about 120,000 Germans and Italians pitted against a like number of British and Commonwealth forces. And yet much was at stake for Hitler in that sideshow: German prestige, the integrity and solidarity of the Pact of Steel, and, not least, control of the Mediterranean Basin, the Balkans, and the Middle East.

The Desert War was governed absolutely by logistics. On September 3, neither side had sufficient strength to crush the other. However, the British had three advantages: Luftwaffe Ultra, which helped them to intercept and smash the convoys supplying the Axis forces; superior naval forces in the Mediterranean Sea; and use of the less-threatened sea route to Egypt via the Cape of Good Hope. London was confident that by October or early November the British Eighth Army would be strong enough to launch an offensive (Crusader), which would crush the Italians and Erwin Rommel’s Afrika Korps and rescue a besieged Commonwealth garrison at Tobruk, which Rommel had bypassed.

The projected large growth in the Atlantic U-boat force did not occur in the fall of 1941. There were several reasons. Problems had mounted at home. There was a shortage of shipyard workers (estimated at 20,000) and torpedo-recovery vessels in the Training Command (only 300 rather than the 1,000 needed). The shortage of shipyard workers resulted in shoddy workmanship in some yards, and many U-boats had to return for extensive and time-consuming repairs before sailing to the Atlantic. The shortage of torpedo-recovery vessels delayed the boats in workup and reduced practice shooting from forty-three to twenty-six torpedoes. The shifting of some Agru Front training flotillaś from the eastern Baltic to Norwegian waters caused other delays and the workup period had to be lengthened from 90 days back to 120 days. As a result, many new U-boats were backing up in the Baltic and Norway, not yet fully fit for combat. In addition, eleven more new VIICs were diverted to the Arctic during the fall.

On September 3, about half the Atlantic force was at sea on combat operations in the Atlantic. Apart from the boats in refit at French bases or routinely returning from patrol, many boats were unavailable for various reasons:

• In response to orders from Hitler, six of the most experienced Type VIIs were being prepped at French bases for transfer to the Mediterranean.

• On orders from the OKM, six new VIIs were assigned to patrol the Arctic.

The first two, U-132 and U-576, replaced the U-81 and U-652, which transferred to the Atlantic force.

• On orders from the OKM, Ritterkreuz holder Jürgen Oesten’s U-106 was diverting to the Azores to escort the blockade-runner Annaliese Essberger into Bordeaux.*

• Three boats, commanded by veteran skippers, were aborting: Helmut Rosenbaum in U-73 with heavy bomb damage incurred off Iceland; Ernst Mengersen in U-101 with disabled engines; Nikolaus Clausen in the new U-129 with a suspected case of diphtheria.

• Herbert Opitz’s new U-206 was also aborting. Opitz had rescued six British airmen who had ditched their aircraft. Although Opitz insisted otherwise, Kerneval believed this act of humanity cramped the boat’s fighting ability.

The assignment of fourteen new boats and two Arctic transfers to the Atlantic force in August enabled Dönitz to deploy an unprecedented number of U-boats to the Atlantic areas. On September 3, thirty-six boats were on patrol or proceeding to patrol in three sectors:

• A group, Markgraf (fourteen boats), southeast of Greenland, to attack east-bound and westbound convoys on the North Atlantic run.

• Two groups, Bosemüller (seven boats) and Kurfürst (eight boats), well to the southwest of the British Isles and west of the Bay of Biscay and the Iberian Peninsula, to attack convoys inbound to or outbound from Gibraltar and Sierra Leone.

• Seven boats, patrolling independently in the South Atlantic, to attack shipping off Sierra Leone and elsewhere on the West African coast.

• Dönitz and his staff were hopeful that notwithstanding the decreasing level of combat experience, the boats would find convoys and turn in good results. After a full year of blindness, German codebreakers at B-dienst had penetrated the Royal Navy’s main operational code (Number 2, Köln in Germany) and had made some progress in cracking a special naval code (Number 3, München in Germany) employed jointly by Great Britain, Canada, and the United States for convoy operations. Although B-dienst incurred the inevitable delays and failures of all codebreakers, the flow of information was deemed sufficient and timely enough to help in finding convoys. It was also hoped that the intelligence picture could be improved by the sighting and tracking reports of the Norwegian- and Bordeaux-based Condors, whose crews had become somewhat more proficient in navigation.

To ensure the secrecy of the U-boat positions from the British, Dönitz had introduced new and stringent measures. All U-boats were to be addressed by the surname of the skipper rather than by number (U-Topp for U-552). Naval grid squares were to be double-enciphered, using encoding tables which were to be closely held and changed frequently. Shore stations were forbidden to keep charts of U-boat positions. A new Enigma for U-boats, employing a fourth internal rotor that vastly increased possible permutations, was nearly ready.*

Lacking naval Enigma keys for September, the British codebreakers could not read Heimisch (Dolphin) traffic currently and fluently. But they had mastered the dockyard code, Werft, and some weather-reporting codes. These and other sources provided sufficient cribs to enable Bletchley Park’s bombes to break back into Heimisch (Dolphin) with a delay of one or two days. This intelligence, combined with more sophisticated land-based HF/DF stations, Traffic Analysis, and RFP and TINA, and U-boat sightings by merchant ships, warships, and Coastal Command aircraft, and the knowledge of and insights into U-boat operations and tactics gained by complete access to Enigma traffic during the summer, enabled the Admiralty to continue evading the U-boats through the fall of 1941 with an astonishing degree of success.

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