HMS Sealion was a Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 S-class

British S class submarine (1931)

The S-class submarines of the Royal Navy were originally designed and built during the modernisation of the submarine force in the early 1930s to meet the need for smaller boats to patrol the restricted waters of the North Sea and the Mediterranean Sea replacing the British H class submarines...

 submarine

Submarine

A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

 which was launched 16 March 1934 and fought in the Second World War

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

.

She had an eventful career after the outbreak of war. Under the command of LCdr (later Rear Admiral) Ben Bryant, she attacked U-21

German submarine U-21 (1936)

German submarine U-21 was a Type IIB U-boat of the German Kriegsmarine during World War II.U-21 was assigned to 1st U-boat Flotilla, and carried out seven operational patrols. She sank six ships for a total of and damaged one warship. On 27 March 1940 U-21 ran aground off Oldknuppen Island...

 off the Dogger Bank in November 1939, but failed to sink her. Her first success was the German merchant August Leonhard, sunk in April 1940 off the Danish island of Anholt

Anholt (Denmark)

Anholt is a Danish island in the Kattegat, midway between Jutland and Sweden, with 171 permanent residents as of 1 January 2010. It is seven miles long and about four miles wide at its widest and covers an area of 21,75 km². Anholt is part of Norddjurs municipality in Region Midtjylland...

. She later attacked the German merchant Moltkefels, but failed to hit her. She fired upon the beached Palime, and unsuccessfully attacked U-62

German submarine U-62 (1939)

German submarine U-62 was a Type IIC U-boat of the German Kriegsmarine that served in World War II. She was produced by Deutsche Werke AG, Kiel, and was commissioned on 21 December 1939....

 in July 1940. She finished her patrol by sinking the Norwegian merchant Toran and attacking but failing to sink the German merchant Cläre Hugo Stinnes in August.

On 5 February 1941 she shelled and sank the Norwegian Hurtigruten

Hurtigruten

Hurtigruten or Hurtigruta is a Norwegian passenger and freight line with daily sailings along Norway's western and northern coast. Sometimes referred to in English as Norwegian Coastal Express, Hurtigruten ships sail almost the entire length of the country, completing the roundtrip journey in 11...

 cargo-passenger ship Ryfylke. In May of that year Sealion unsuccessfully attacked U-74. In July she attacked French shipping, sinking the French fishing vessels Gustav Eugene and Gustav Jeanne, and on succeeding days, Christus Regnat and St Pierre d'Alcantara.

She was one of a number of submarines ordered to track the German battleship Bismarck

German battleship Bismarck

Bismarck was the first of two s built for the German Kriegsmarine during World War II. Named after Chancellor Otto von Bismarck, the primary force behind the German unification in 1871, the ship was laid down at the Blohm & Voss shipyard in Hamburg in July 1936 and launched nearly three years later...

 before her eventual sinking.

Towards the end of 1941 she sank the Norwegian tanker Vesco and the Norwegian merchant Island.

She was scuttled as an ASDIC target off the Isle of Arran

Isle of Arran

Arran or the Isle of Arran is the largest island in the Firth of Clyde, Scotland, and with an area of is the seventh largest Scottish island. It is in the unitary council area of North Ayrshire and the 2001 census had a resident population of 5,058...

on 13 March 1945.