German U-boats, or Unterseebooten, played a significant role in Germany’s naval strategy during World War I.

Employed by the German Imperial Navy, these submarines aimed to disrupt Allied supply lines, engage in unrestricted submarine warfare, and challenge the naval supremacy of the British Royal Navy.

Here we will delve into a comprehensive exploration of German U-boats, including their construction, crews, operational success, the ships they sank, and the fate that awaited them.

Construction of German U-Boats

German U-boats were constructed in various dockyards across Germany, each contributing to the expansion of the submarine fleet. Notable dockyards involved in U-boat construction during World War I included:

Germaniawerft in Kiel: The Germaniawerft shipyard played a pivotal role in building U-boats, producing submarines such as the Type U-31 and Type U-35. These vessels were known for their technological advancements, including diesel-electric propulsion systems, which increased their range and efficiency.

Up close and personal. The Linda Blanche is sunk by SM U-21 during WW1.

Howaldtswerke-Deutsche Werft (HDW) in Kiel: HDW was another significant dockyard responsible for U-boat construction. It contributed to the production of submarines such as the Type U-66 and Type U-139, known for their innovative designs and operational capabilities.

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AG Weser in Bremen: AG Weser played a crucial role in U-boat production, including the construction of submarines such as the Type U-151. These boats were part of Germany’s response to the escalating naval blockade imposed by the Allied powers.

The construction process involved the assembly of hull sections, installation of engines and machinery, fitting of torpedo tubes, and equipping the submarines with advanced periscopes, hydrophones, and torpedoes. These cutting-edge technologies made German U-boats formidable underwater threats.

U-Boat Crews

The crews of German U-boats were composed of highly skilled officers and enlisted men. Each submarine’s crew size varied depending on the type and size of the U-boat. A typical crew included officers, non-commissioned officers, and enlisted sailors.

Some of the officers and crew of the German U-Boat U-9. Each relied on the other.

Officers aboard U-boats held crucial roles in commanding the vessel, making tactical decisions, and operating the complex machinery. They received specialised training in submarine warfare and were often experienced naval officers with a deep understanding of naval tactics and navigation.

Non-commissioned officers played vital roles in overseeing specific departments such as engineering or navigation. They ensured the smooth operation of the U-boat, coordinating the efforts of the enlisted crew members and providing technical expertise in maintaining the vessel’s systems.

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Enlisted sailors formed the backbone of the U-boat crews. These skilled sailors performed a variety of duties, including operating machinery, maintaining equipment, handling weapons, and carrying out day-to-day tasks necessary for the smooth functioning of the submarine.

Their discipline, efficiency, and adaptability were crucial for the success of U-boat missions.

Success of German U-Boats

German U-boats achieved significant success during World War I, disrupting Allied shipping and posing a severe threat to naval operations. They employed various tactics, including unrestricted submarine warfare, to target merchant ships and naval vessels of the Allied powers.

U-Boat U9 leaves port to go into the Atlantic. It was an early German submarine.

The success of German U-boats was particularly pronounced during the early years of the war when the British Royal Navy struggled to develop effective countermeasures. The U-boats’ ability to strike from concealment beneath the surface of the water provided them with a tactical advantage, allowing them to launch surprise attacks on unsuspecting ships.

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U-boats sank numerous ships, causing economic and logistical damage to the Allies. By targeting merchant vessels, they aimed to cripple Britain. Much of Britain’s food came from overseas along with armaments and other crucial supplies. By sinking these vessels the U-boats were bleeding the British of valuable goods and food.

Ships Sunk

German U-boats targeted a wide range of vessels, including merchant ships, passenger liners, and warships. Notable sinkings by U-boats included:

RMS Lusitania:

One of the most infamous sinkings of World War I was the British passenger liner RMS Lusitania. On May 7, 1915, U-20, commanded by Kapitänleutnant Walther Schwieger, torpedoed the Lusitania off the coast of Ireland, resulting in the loss of over 1,100 lives, including civilians and Americans. This incident had a significant impact on public opinion and played a role in shaping America’s entry into the war.

HMS Pathfinder:

In September 1914, U-21, commanded by Kapitänleutnant Otto Hersing, sank the British cruiser HMS Pathfinder off the east coast of Scotland. This was the first successful torpedo attack on a warship by a U-boat during the war.

HMS Audacious:

The Battleship HMS Audacious was torpedoed and sunk by a German U-boat. Some still claim it was a mine however.

In October 1914, U-29, commanded by Kapitänleutnant Otto Weddigen, successfully torpedoed the British battleship HMS Audacious off the coast of Ireland. Although the battleship did not sink immediately, it eventually succumbed to internal damage and had to be scuttled. Mystery still surrounds its sinking as some say it was a mine. It was flying the Submarine Warning flag when it sank!

HMS Aboukir, Hogue, and Cressy:

In September 1914, U-9, commanded by Kapitänleutnant Otto Weddigen, launched torpedoes at the British cruisers HMS Aboukir, Hogue, and Cressy. All three cruisers were sunk in quick succession, resulting in the loss of over 1,400 British sailors.

HMS Aboukir, a British First WW1 cruiser that would later be sunk by German U-boats.

SS Arabic:

In August 1915, U-24, under the command of Kapitänleutnant Rudolf Schneider, torpedoed and sank the British passenger liner SS Arabic in the eastern Mediterranean. The sinking resulted in the deaths of 44 people. This included three Americans, which led to increased tensions between Germany and the United States.

HMS Formidable:

On January 1, 1915, U-24 struck again, sinking the British battleship HMS Formidable off the coast of Devon, England. The attack occurred during stormy weather, making rescue efforts challenging. The sinking of HMS Formidable resulted in the loss of 547 British sailors.

SS Llandovery Castle:

In June 1918, U-86, commanded by Kapitänleutnant Helmut Brümmer-Patzig, attacked and sank the Canadian hospital ship SS Llandovery Castle in the Atlantic Ocean. The ship was clearly marked as a hospital ship. Still U-86 fired torpedoes, leading to the deaths of 234 people, including medical personnel and patients.

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These are just a few notable examples of the ships sunk by German U-boats during World War I. U-boats targeted both military and civilian vessels, causing significant losses and disrupting Allied supply lines.

Fate of German U-Boat Crews

While German U-boats inflicted substantial damage on Allied shipping, they also faced significant losses during World War I. The exact number of U-boats sunk is subject to debate, but estimates suggest that around 178 U-boats were lost during the war.

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The fate of German U-boat crews varied throughout the war. Some U-boats returned safely to their bases after successful missions, while others faced the dangers of the sea, enemy attacks, or mechanical failures.

The Lusitania. Arguably one the most infamous ‘victims’ of a U-boat.

For the crews of U-boats that were sunk or disabled, the outcomes differed. In some instances, crew members were able to abandon ship and were subsequently captured by the enemy. They became prisoners of war, enduring captivity until the end of the conflict. The conditions for POWs varied, but many endured hardships and privations during their internment.

For crews that managed to escape from a sinking U-boat, survival in the open sea presented its own challenges. Exposure, lack of food and water, and the threat of enemy patrols added to the dangers they faced. Some crew members were rescued by friendly forces or neutral vessels, while others perished at sea.

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However, it’s important to note that not all U-boat crews met a grim fate. Many U-boats returned to base, their crews celebrated as heroes for their successful operations. The crews were highly skilled and resilient, enduring long patrols and the constant dangers of submarine warfare.

Into the Future

German U-boats played a significant role in World War I, employing innovative technology and tactics to disrupt Allied shipping. The construction of U-boats took place in various dockyards across Germany, with advancements in submarine design and technology contributing to their success.

The U-boat successes of the Great War had a huge impact into WW2 and even today with the modern use of nuclear powered submarines.