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Books by John Barratt

Armada 1588

The Battle of Marston Moor

The Civil War in South-West England 1642-1646

The First Battle of Newbury: 1643

Cavalier Generals

The Great Siege of Chester

The Battle for York: Marston Moor 1644

Cavalier Generals

Re-birth of the U-boat
Re-birth of the U-boat
by John Barratt

The devastation wrought by German U-boats on Allied merchant shipping during World War I brought Imperial Germany nearer to victory than the efforts of any of her other armed forces. It was with memories of this that the Allies, by the terms of the Treaty of Versailles (1919) prohibited the small Navy of the new German Republic from having any submarines. 

Yet almost before the Treaty had been signed, Germany was working to ensure that skills and expertise in building U-boats should be preserved for future use. In 1922 a "Submarine Development Bureau" was set up in Holland, employing the best of the German U-boat designers, disguised as an ordinary Dutch shipbuilding firm. U-boats were built for Spain, Turkey and Finland, and German seamen given experience on "proving trials". When the Anglo-German Naval Agreement of 1935 once more permitted Germany to build submarines up to parity with Britain, plans for the Kriegsmarine's new U-boat arm were already well advanced. Parts for several U-boats were secretly stored ready for assembly, and the first small coastal U-boat (U1) was actually launched on the day before the Naval Agreement was signed. By the end of 1935, the first U-boat flotilla, "Flotilla Weddigen", was in service. 

These small Type II coastal submarines provided excellent training vessels for Germany's expanding U-boat arm, and the Flotilla's commander, Kapitan sur Zee Karl Donitz, was a firm believer in the value of the submarine, even though only two and a half of his 35 years' service in the Navy had actually been spent in U-boats. Grand Admiral Raeder, commander-in-chief of the Kriegsmarine, had never seriously expected that Germany would be permitted to operate submarines, and as a result had given no real thought as to whom should command a U-boat force. Donitz seems to have been appointed Flag Officer Submarines simply because he happened to be available at the time. He was to prove an inspired choice.

Prior to the outbreak of war, Donitz had very little influence on U-boat construction, which was controlled by a separate department in the Supreme Naval Command. Although Donitz wanted to concentrate construction on the Type VII U-boats, with sufficient range to operate in the Atlantic, he found it hard to gain support within the Naval High Command, the majority of whose personnel favoured the massive Plan Z building programme, aimed at developing a powerful surface fleet. Thus the outbreak of war in September 1939 found Donitz with a total of only 57 U-boats, of which only about 20 were suitable for ocean-going operations, instead of the massive force of 300 which he had been calling for.


The impression sometimes given that Donitz controlled the U-boat campaign virtually single-handed is of course incorrect. On the outbreak of war the command structure of the U-boat arm was re-structured. Donitz was appointed Flag Officer for Submarines, responsible for all U-boat operations. His headquarters was initially at Wilhelmshavem but after the occupation of France was based at Paris or Lorient, transferring to Berlin in March 1943. Even after he became Commander-in Chief of the German Navy in 1943, Donitz also retained command of the U-boat arm. Donitz took a close personal interest in the U-boat service, frequently visiting the Operations Room, greeting returning U-boat crews, and writing personal letters of condolence to the families of those lost.

U-boat command was split into two departments, "Operations", for the duration of the war under Vice-Admiral Eberhard Godt, was responsible for controlling U-boats whilst actually at sea. "Organisation", under Vice-Admiral Hans-Georg von Freideburg, dealt with training, supplies and personnel.

The U-boats themselves were organised into flotillas, of which 33 were created before or during the war, although about four of these were never operational. The flotillas were of two kinds, training and operational. Training flotillas operated mainly in the Baltic, in areas thought to be out of enemy reach. The operational flotillas began the war in German bases, but following the tide of German conquests later operated from French Atlantic ports, Norway, the Mediterranean, and even the Black Sea. Flotillas were supply and organisational units, rather than having any specific tactical responsibilities. 

The Men

Donitz was fortunate in having the services as commanders of a number of officers who had seen service in the U-boat arm during World War I. But increasingly as the war went on the officers and men of the U-boat force would be new, and usually young, in their late teens and twenties. Contrary to the impression sometimes give, the vast majority of U-boat commanders performed their duties with as much humanity as was possible in the circumstances, and it is significant that after the war senior Allied naval officers spoke up for them when threatened with prosecution for war crimes.

Throughout the war, most U-boat men were volunteers, and had to meet a very high standard. Only about one in ten of potential volunteers were actually accepted. Despite the daunting hazards of U-boat service, which in the latter half of the war almost amounted to a death sentence, morale among the U-boat crews remained generally high. Not only were they sustained by the promise of new and more effective weapons, but their service conditions were superior to those in the rest of the Kriegsmarine. Pay and allowances were almost double, special trains were arranged to bring U-boat crews home on leave, and the U-boat bases were well supplied with a range of recreational facilities.

Discipline aboard many U-boats was noticeably less formal than elsewhere, mainly being dictated by the attitude of individual commanders. The crew of a new U-boat usually trained together on their vessel for a period of about two months before being made operational, and the training was designed to mould them into a close-knit unit, confident in each other and their abilities.

The privileges of a U-boat man were hard-earned. Quite apart from the ever-present dangers of attack, increasing steadily throughout the war, and the perils of the sea, conditions aboard a U-boat would have been regarded as intolerable by most civilians. Quarters were cramped in the extreme. The captain might have a small cubby-hole as a "cabin", but the majority of the crew slept and messed in a tiny area, often sharing their quarters with the reserve torpedoes. The Type VII U-boat, for example, mainstay of the Atlantic campaign, was only 220 feet long and 20 feet across at its widest point. It normally carried a crew of approximately 45 officers and men. There were only enough bunks to be occupied on a rota system, and normally only one toilet for the entire crew. Smoking was not permitted, and facilities for washing and shaving rare. Clothing, and the interior of the U-boat, were almost continuously damp, and the atmosphere stale and evil-smelling. Cooking facilities were basic, and by the end of a voyage food supplies were often beginning to rot and go bad.

The U-Boats

The first submarines to be built for the Kreigsmarine, the Type IIC, were small coastal vessels, unsuitable for the mid and eastern Atlantic operations envisaged in Donitz's strategy. They were mainly employed in the Baltic for training purposes.

Mainstay of the U-boat fleet for virtually the entire war was the Type VIIC. With a surface displacement of 770 tons, and 1,070 tons submerged, they had a crew of between 44 and 56, and a maximum surface speed of 17 knots, and 4 knots when submerged. With a surface range at cruising speed of 8,500 nautical miles and 80 when submerged, the Type VIIC proved capable of carrying the U-boat war to the eastern seaboard of the United States. The Type VIIC had 5 torpedo tubes, 4 in the bow and one in the stern, and carried a total of 14 torpedoes.

Introduced shortly after the Type VIIC, the Type IXC was also important in the Atlantic campaign. Larger than the Type VIIC, the Type IXC displaced 1,120 tons on the surface and 1,540 tons submerged. She carried a crew of about 48, and had a speed approximately the same as that of the Type VIIC. The main advantage of the Type IXC was her range, 13,450 nautical miles on the surface, though only 63 miles when submerged, because of her greater displacement. She was also more heavily armed than the Type VIIC, with six torpedo tubes and capacity for 22 torpedoes. The main disadvantage of the Type IXC compared with the Type VIIC lay in a longer submerging time.

Though these two types were built in by far the greatest numbers, they were not the only U-boats to be employed in the war. Several variants of the Type IX were produced, and larger vessels, the Types XB and XIV, made an appearance in small numbers in the role of unarmed supply submarines or "milch cows" designed to refurbish the attack submarines with torpedoes, fuel and foodstuffs. Very vulnerable, especially to air attack, they proved easy victims to Allied forces and were steadily hunted down.

Of great potential significance both for the course of the war and for future submarine development, were the various experimental types of U-boat introduced or planned, mainly in the later stages of the war. The U-boats commissioned up until about the end of 1942 were not in fact "submarines" in the modern sense of the term, vessels in other words capable of operating almost entirely under water. They are better described as "submersibles", which operated mainly, and often most effectively, on the surface. The new generation of vessels under development in the closing years of the war began to change the face of undersea warfare. 

Most revolutionary, if it had appeared in time, would have been the so-called "Walther" U-boat, named after its inventor, Helmuth Walther, a minor employee at the Germania U-boat works in Kiel, who in 1934 approached the Naval Command with plans for a radical new type of submarine. Powered by a geared turbine, running on a hydrogen peroxide based fuel, the proposed U-boat would be capable of submerged speeds of 25 knots, greater than many surface anti-submarine vessels. Apathy, lack of resources and scepticism in the Naval High Command meant that developments were slow, and production promised to be to complex and hazardous for mass production. By 1942 it was obvious that the "Walther" would not be available in time to influence the current struggle.

A meeting between Donitz and Walther in November 1942 led to the decision to concentrate in the interim on the "electro" submarine. These vessels had much greater battery capacity than the conventional U-boats, enabling greater underwater speeds and endurance, and, with the addition of the "Schnorchel" device to replenish air when submerged, able to stay under water for long periods of time. The "Schnorchel" was not in fact a German invention, having been used by Dutch long-range submarines prior to the war, but it promised greatly to reduce the vulnerability of the U-boat. Testing began in September 1943, with conversion kits being built for existing U-boats, but the first few newly equipped vessels were not in service until June 1944.

The "Schnorchel" device could sometimes be detected by radar or keen-eyed lookouts in calm weather, but although virtually impossible to spot in rougher conditions, these same situations often caused problems of their own. The float valve which closed the "Schnorchel" if its intake became submerged often caused a sharp fall in air pressure in the U-boat as air was sucked into the diesels, with resulting breathing difficulties and sometimes injury such as perforated eardrums. On several occasions air inside U-boats became so foul that crews were actually suffocated.

The outcome of Donitz's decision were the Types XXIII and XXI. The Type XXIII was a coastal U-boat, with a range of 200 nautical miles submerged at a cruising speed of 4 knots. The larger Type XXI was a potentially very formidable weapon, which had a range of up to 15,500 nautical miles on the surface, and 365 miles submerged at 5 knots, though it could reach a submerged speed of 10 knots for just over 100 miles. Though claims that, had they appeared in 1943, these vessels would have won the Battle of the Atlantic for Germany are probably overstated, even as late as 1945, their possible use caused the allies grave concern, and it was fortunate that the war ended with only a few Type XXIII and only one Type XXI operational.

U-boat Construction

In July 1943 it was agreed at a meeting between Donitz and Hitler that construction of the new types of U-boat should be given priority. No further vessels of the older types were to be laid down, though 250 in various stages of construction were to be completed, to tide the U-boat arm over until the new types came into service.

Hitherto, submarine construction had been a navy responsibility. But it was clear that under the existing system the Type XXI would not enter service in significant numbers before 1946, obviously far too late. Responsibility for U-boat construction was transferred to Albert Speer's Ministry of Arms and Munitions, and an industrialist, Otto Merker, placed in charge of the building programme. Merker decided to adopt a "prefabrication" method of construction inspired by the US "liberty ship" system. This was intended to reduce construction time by up to one third. Different sections of the U-boat were completed by manufacturers in up to eleven widely scattered locations. These were shipped to assembly centres on the coast by barge along Germany's inland waterway system.

Partly intended to reduce damage by air attack, this system in fact proved to be fatally vulnerable to the concerted Allied bombing assault on the internal waterway network which now began. As a result the building programme lagged steadily further behind. By the end of 1944, 60 Type XXIs had been completed and 30 more had been launched. About 31 Type XXIIIs had been finished, and 23 more were building. But quite apart from the delays caused by Allied bombing, many of the vessels suffered major problems due to poor materials or workmanship. The war would end before these problems could be overcome.


If Donitz had been frustrated in his hopes of priority being given to the U-boat arm, he had, undeterred, given considerable attention to the development of effective tactics. At this time the submarine was considered irrelevant by many in naval circles, especially in the British Royal Navy, but also in some quarters of the German Naval High Command. The submarine, it was argued, was too slow, and too easily detected by the British ultra-sonic detection device known as "asdic". As late as 1937, the British Admiralty declared that the submarine would never again be a major threat. Donitz did not share this belief.

The tactics he and his team developed had four basic ideas. Previously, submarine commanders had been taught to attack at a range of at least one and a half miles. This, it was believed, would minimize the risk of detection by asdic, but it also demanded the expenditure of a full salvo of torpedoes in order to achieve a great enough "spread", with a very poor standard of accuracy.

Donitz, reasoning that there was no proof that the "asdic" detection system was actually as effective as had been claimed, ordered his commanders to close in to about 550 yards before attacking. This had the major advantage of increased the chances of obtaining more than one hit with a salvo of four torpedoes. During the war some U-boat commanders like the "ace", Otto Kretschmer, would develop this tactic to the point of actually sailing into the middle of convoys and picking out the best targets.

Donitz also adopted the tactic of night-time surface attacks. Indeed his U-boats generally only submerged to evade the enemy or escape adverse weather conditions. A U-boat on the surface, especially at night, presented a very small target, and both speed and endurance were significantly greater than when operating submerged.

Although U-boats sometimes used gunfire to sink merchant ships, mainly to economise on their stock of torpedoes, the latter, so far as Donitz was concerned, remained their chief and most effective weapon. Certainly he impressed on his commanders the need to avoid surface combat, in which the U-boat's pressure hull was fatally vulnerable to even one hit.

The tactic with which Donitz is usually most closely associated is the "wolf pack" attack. This had in fact first been suggested during World War I, but it was left to Donitz to refine and put it into practice. As it eventually evolved, the tactic called for a group of U-boats to be spread out across the anticipated path of a convoy. During daylight hours they would sail towards the convoy, usually at about 10 knots, whilst after dusk, in order not to miss their target in the darkness, they would turn and sail in the same direction as the convoy. The first U-boat to spot the convoy would signal its position to U-boat headquarters, and send out homing signals to assemble the rest of the pack. When the attack actually began, each commander would be left to decide his own tactics. The original wide spread of the pack meant that continuous attacks were often mounted for several days as fresh U-boats came up with the convoy.

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Williamson, Gordon and Darko Pavlovic. U-Boat Crews, 1914-45, London, 1945.

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Copyright © 2002 John Barratt.

Written by John Barratt. If you have questions or comments on this article, please contact John Barratt at:

About the author:
John Barratt has authored many books to include: Armada 1588,  The Battle of Marston Moor, The Civil War in South-West England 1642-1646, and Cavalier Generals.

Published online: 12/15/2002.
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