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Maritime History: U-Boats

Written by: John Maguire

The word "U-boat" comes from the German word "Unterseeboot," which translates to "undersea boat." Though the term has applied to many different submarines, it often evokes images of war vessels used during World War I and World War II. U-boats were used for many different tasks, including fighting, spying, commerce raiding, and enforcing blockades. The U-boat was a highly versatile ship and could be found around major port cities, cruise destinations, inland seaways, and the open sea.

Early U-Boats (1850-1914)

Germany first started testing submarines in 1851. The three-man Brandtaucher sank in the harbor of Kiel, which would become one of Germany's major cruise departure ports. It wouldn't be until 1903 that the first fully functional German submarine was created, the Forelle. This would be followed by the SM U-1, the first submarine to be commissioned by the German government; only one of these would be built before this model was quickly replaced by the SM-2 in 1908, doubling the number of torpedo tubes. Improvements continued with the SM U-19, which would be built in 1912 with a more powerful diesel engine.

  • The Brandtaucher: The Brandtaucher was located in 1887 and raised, and it can be seen on display today.
  • The Forelle: The Forelle was sold to Russia and used in the Russo-Japanese War.
  • The SM U-19: This U-boat changed the engine design for submarines.

World War I (1914-18)

At the start of World War I, the German navy had 48 submarines, but by the end of the war, this number would grow to 375. On Sept. 5, 1914, the HMS Pathfinder became the first ship to be sunk by a submarine using a self-propelled torpedo. It was sunk by U-21. U-17 would sink the first merchant vessel of the war on Oct. 20, 1914. German subs would sink more than 5,000 ships over the course of the war and lose 178 submarines to enemy actions. Allied forces lost more than 12,850,000 tons of goods due to the U-boat campaign. The sinking of the RMS Lusitania and the SS Sussex caused public perception of the German war effort to change, especially in America, where these ships had been seen as civilian vessels used for discount cruises and not military targets.

Interwar Years (1919-39)

After the Treaty of Versailles in 1919, the German navy was limited in how many ships they could have in total, and they were not allowed to have any submarines at all. However, Germany did maintain a submarine design office in the Netherlands and a torpedo research center in Sweden. During the leadup to World War II, Germany started building ships for research purposes and in secret. By the start of the war, Germany already had 65 new U-boats.

  • Continued U-Boat Research: Germany still studied U-boat technology even though they were not allowed to build any new submarines after World War I.
  • U-2: In the 1930s, the Germans worked to rebuild their U-boat fleet.
  • The Anglo-German Naval Agreement: Signed in 1935, this agreement was an attempt to limit the German navy in the hopes of avoiding another conflict.

World War II (1939-45)

At the start of World War II, German U-boat attacks were very effective. Led by the workhorse Type VII and the larger Type IX U-boats, the German navy experienced great success for the first year and a half of the war. However, as the war went on, technological advancements in radar and sonar led to U-boat techniques changing. Soon, wolf packs of U-boats would work together to quickly destroy targets. During World War II 1,156 U-boats were built. They would sink more than 3,500 ships in the Atlantic, but the German navy lost 784 ships.

Post-World War II and Cold War (After 1945)

After World War II, harsh sanctions were placed on Germany, and they would not have a navy again until 1955. The first U-boats in the new navy were two sunken Type XXIIIs and a Type XXI that had been raised. Later, in the 1960s, Germany would build the Type 201 and then the Type 205. They brought back the U designation but started fresh with the U-1. The U designation is still being used, with the newest ship being U-36, a Type 212 commissioned in 2016.

U-Boat Technological Developments

The U-boat has seen many different changes over the past 150 years. From very humble origins to becoming one of the most useful and feared ships on the ocean, these vessels have had to be adaptable. The modern U-boat uses an air-independent propulsion system that is safer than diesel, cheaper than nuclear subs, and quieter than both.

U-Boats, Submarines, and Naval Ships