German U-boat

German submarine

War & ConflictPolitics & Government
German U-boat
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Overview

What happened

U-boats are naval submarines operated by Germany, especially during World War I and World War II.

Date

May 9, 1941

Location

The North Atlantic, where U-boats targeted Allied convoys and supply ships

Key people

Captain Joe Baker-Cresswell and Kapitänleutnant Fritz-Julius Lemp were instrumental in the U-110's capture and subsequent intel extraction

Why it matters

This event highlighted the critical role of codebreaking in modern warfare, allowing the Allies to anticipate and counter German naval operations

What was German U-boat?

U-boats are naval submarines operated by Germany, especially during World War I and World War II. The term is an anglicized form of the German word U-Boot [ˈuːboːt] , a shortening of Unterseeboot (lit. 'under-sea boat'). Austro-Hungarian Navy submarines were also known as U-boats. U-boats are especially known for their use in unrestricted submarine warfare in both world wars, attempting to disrupt merchant traffic towards the UK and force the UK out of the war. In World War I, Germany intermittently waged unrestricted submarine warfare against the UK: a first campaign in 1915 was abandoned after strong protests from the US but in February 1917 the Germans, facing deadlock on the continent, saw no other option than to resume the campaign.

Sea mines are loaded in a UC coastal submarine in the harbour of Zeebrugge
Sea mines are loaded in a UC coastal submarine in the harbour of Zeebrugge
Related books
Iron Coffins cover Iron Coffins Herbert A. Werner · 1969 Seizing the enigma cover Seizing the enigma David Kahn · 1996 The defeat of the German U-boats cover The defeat of the German U-boats David Syrett · 1994 Silent Hunters cover Silent Hunters Theodore P. Savas · 1990 Black May cover Black May Michael Gannon · 1998
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Background and consequences

The renewed campaign failed to achieve its goal mainly because of the introduction of convoys. Instead the campaign ensured final defeat as the campaign was a contributing factor to the entry of the US in the First World War. In World War II, Karl Dönitz, supreme commander of the Kriegsmarine's U-boat arm (Befehlshaber der Unterseeboote), was convinced the UK and its convoys could be defeated by new tactics, and tried to focus on convoy battles. Though U-boat tactics initially saw success in the Battle of the Atlantic, greatly disrupting Allied shipping, improved convoy and anti-submarine tactics such as high-frequency direction finding and the Hedgehog anti-submarine system began to take a toll on the German U-boat force.

A Type XB submarine sinking in the Atlantic. On the foredeck the vertical mineshafts are visible.
A Type XB submarine sinking in the Atlantic. On the foredeck the vertical mineshafts are visible.
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Why it matters

This ultimately came to a head in May 1943, known as Black May, in which U-boat losses began to outpace their effect on shipping.

Related on thisDay

Capture of U-110 — May 9, 1941

41 Allied ships sunk: U-110's capture near Iceland on May 9, 1941, gave the British Navy a crucial advantage in the Battle of the Atlantic

Use the dated article for the day-specific account; use these references to check the event record and explore its wider historical context.

Date article: Capture of U-110 — May 9, 1941Wikipedia source
Cite this page
MLA

“German U-boat.” thisDay, thisday.info/history/german-u-boat/. Accessed 19 Oct. 2026.

APA

German U-boat. (n.d.). thisDay. Retrieved October 19, 2026, from https://thisday.info/history/german-u-boat/

Chicago

“German U-boat.” thisDay. Accessed October 19, 2026. https://thisday.info/history/german-u-boat/.

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