HMS Amethyst was a Modified Black Swan-class

Black Swan class sloop

The Black Swan class and Modified Black Swan class were two classes of sloop of the Royal Navy and Royal Indian Navy. Thirteen Black Swans were launched between 1939 and 1943, including four for the Royal Indian Navy; twenty-four Modified Black Swans were launched between 1942 and 1945, including...

 sloop

Sloop-of-war

In the 18th and most of the 19th centuries, a sloop-of-war was a warship with a single gun deck that carried up to eighteen guns. As the rating system covered all vessels with 20 guns and above, this meant that the term sloop-of-war actually encompassed all the unrated combat vessels including the...

 of the 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...

. She was laid down by Alexander Stephens and Sons of Linthouse

Linthouse

Linthouse is a district in the Scottish city of Glasgow. It is situated south of the River Clyde. It is immediately west of Govan, and although it is often referred to locally as 'Govan' due to its closeness, it is in fact a distinct area .Linthouse was home to the shipbuilder...

, Govan

Govan

Govan is a district and former burgh now part of southwest City of Glasgow, Scotland. It is situated west of Glasgow city centre, on the south bank of the River Clyde, opposite the mouth of the River Kelvin and the district of Partick....

 Scotland

Scotland

Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...

 on 25 March 1942, launched on 7 May 1943 and commissioned on 2 November 1943, with the pennant number

Pennant number

In the modern Royal Navy, and other navies of Europe and the Commonwealth, ships are identified by pennant numbers...

 U16. After World War II she was modified and redesignated as a frigate

Frigate

A frigate is any of several types of warship, the term having been used for ships of various sizes and roles over the last few centuries.In the 17th century, the term was used for any warship built for speed and maneuverability, the description often used being "frigate-built"...

, and renumbered F116.
During World War II, Amethyst was deployed mostly on anti-submarine patrols and escort duties. On 20 February 1945 she attacked and sank the U-boat

U-boat

U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...

 U-1276

Unterseeboot 1276

German submarine U-1276 was a Type VIIC/41 U-boat of the Kriegsmarine. Bremer Vulkan of Bremen-Vegesack laid down her keel on July 13, 1943. She was commissioned April 6, 1944 with Oberleutnant Karl Heinz Wendt in command...

 with depth charge

Depth charge

A depth charge is an anti-submarine warfare weapon intended to destroy or cripple a target submarine by the shock of exploding near it. Most use explosives and a fuze set to go off at a preselected depth in the ocean. Depth charges can be dropped by either surface ships, patrol aircraft, or from...

s.