The Castle-class minesweeper was a highly seaworthy

naval trawler Naval trawlers are vessels built along the lines of a fishing trawler but fitted out for naval purposes; they were widely used during the First and Second World Wars. Some—known in the Royal Navy as "Admiralty trawlers"— were purpose-built ...

adapted for

patrol A patrol is commonly a group of personnel, such as law enforcement officers, military personnel, or security personnel, that are assigned to monitor or secure a specific geographic area. Etymology From French ''patrouiller'', from Old Frenc ...

anti-submarine warfare Anti-submarine warfare (ASW, or in older form A/S) is a branch of underwater warfare that uses surface warships, aircraft, submarines, or other platforms, to find, track, and deter, damage, or destroy enemy submarines. Such operations are typi ...

and

minesweeping Minesweeping is the practice of the removal of explosive naval mines, usually by a specially designed ship called a minesweeper using various measures to either capture or detonate the mines, but sometimes also with an aircraft made for that ...

duties and built to Admiralty specifications. Altogether 197 were built in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...

between 1916 and 1919, with others built in

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tota ...

India India, officially the Republic of India ( Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the ...

and later

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 List of islands of New Zealand, smaller islands. It is the ...

. Many saw service in the

Second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...

First World War

The Castle class originated with the

commercial trawler A fishing trawler is a commercial fishing vessel designed to operate fishing trawls. Trawling is a method of fishing that involves actively dragging or pulling a trawl through the water behind one or more trawlers. Trawls are fishing nets tha ...

''Raglan Castle'' of 1915, taken up for

Royal Navy The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by Kingdom of England, English and Kingdom of Scotland, Scottish kings from the early medieval period, the first major maritime engagements were foug ...

service. The design was adapted by Smith's Dock Company Ltd to Admiralty requirements for building in quantity. During

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...

, 145 were built in the United Kingdom for the Admiralty. The names of the vessels were derived from the official crew rosters of ships at the

Battle of Trafalgar The Battle of Trafalgar (21 October 1805) was a naval battle, naval engagement between the British Royal Navy and the combined fleets of the French Navy, French and Spanish Navy, Spanish Navies during the War of the Third Coalition (August–De ...

. Non-standard ships included in the class varied between and , with dimensions varying between length and

beam Beam may refer to: Streams of particles or energy * Light beam, or beam of light, a directional projection of light energy ** Laser beam * Particle beam, a stream of charged or neutral particles **Charged particle beam, a spatially localized g ...

. The first standard vessel, ''Nathaniel Cole'', was delivered in May 1917. After the war 52 further ships on order were completed as

fishing vessel A fishing vessel is a boat or ship used to catch fish in the sea, or on a lake or river. Many different kinds of vessels are used in commercial, artisanal and recreational fishing. The total number of fishing vessels in the world in 2016 was ...

s and many of the minesweepers were converted for commercial use. 20 ships were also cancelled, but many were completed by the shipbuilders for commercial owners. The Admiralty also ordered 60 Castle-class trawlers from Canadian shipyards, the TR series, which were loaned to the

Royal Canadian Navy The Royal Canadian Navy (RCN; french: Marine royale canadienne, ''MRC'') is the naval force of Canada. The RCN is one of three environmental commands within the Canadian Armed Forces. As of 2021, the RCN operates 12 frigates, four attack subma ...

for seaward defence of the

east coast of Canada Atlantic Canada, also called the Atlantic provinces (french: provinces de l'Atlantique), is the region of Eastern Canada comprising the provinces located on the Atlantic coast, excluding Quebec. The four provinces are New Brunswick, Newfoundla ...

. Some entered service with the

United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...

. Nine ships were also built in

with teak planking on steel frames.

Second World War

Many Castle-class trawlers were among the civilian trawlers requisitioned by the Royal Navy for use in World War II. The majority were employed as minesweepers, with others serving as auxiliary patrol vessels, boom defense vessels,

danlayer A danlayer was a type of vessel assigned to minesweeping flotillas during and immediately after World War II. They were usually small trawlers, fitted for the purpose of laying dans. A dan is a marker buoy which consists of a long pole moored to t ...

s, Essos (fuel carriers), torpedo recovery vessels and water carriers. Many had multiple roles over the course of the war. After the end of the war, most of those that had survived were either sold or returned to their owners.

German captured

Early in

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...

, ten Canadian-built trawlers that had been sold into commercial service after World War I with a number of European countries were captured by the Germans when they overran

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan ar ...

Belgium Belgium, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to ...

and

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...

and put in

Kriegsmarine The (, ) was the navy of Germany from 1935 to 1945. It superseded the Imperial German Navy of the German Empire (1871–1918) and the inter-war (1919–1935) of the Weimar Republic. The was one of three official branches, along with th ...

service.

New Zealand additions

In 1940, the New Zealand Government, facing a requirement for minesweepers to operate in home waters, directed the building of 13 Castle-class naval trawlers in New Zealand to add to the two vessels, ''James Cosgrove'' and ''Wakakura'', they had previously purchased. The Castle-class design was chosen over more modern alternatives because it was simple enough to be built with the country's limited ship construction facilities.

Ships in class

Non-standard

Standard

Cancelled

Canadian-built

See TR series minesweeping trawler.

Indian-built

New Zealand-built

See Castle class trawlers of the Royal New Zealand Navy.

References

Sources

* * * * * * * * * * {{Refend Mine warfare vessel classes Ship classes of the Royal Navy