The J, K and N class was a class

Ship class

A ship class is a group of ships of a similar design. This is distinct from a ship-type, which might reflect a similarity of tonnage or intended use. For example, the is a nuclear aircraft carrier of the Nimitz class....

 of 24 destroyer

Destroyer

In naval terminology, a destroyer is a fast and maneuverable yet long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against smaller, powerful, short-range attackers. Destroyers, originally called torpedo-boat destroyers in 1892, evolved from...

s 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...

 launched in 1938. They were a return to a smaller vessel, with a heavier torpedo

Torpedo

The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

 armament, after the Tribal class

Tribal class destroyer (1936)

The Tribal class, or Afridi class, were a class of destroyers built for the Royal Navy, Royal Canadian Navy and Royal Australian Navy that saw service in World War II...

 that emphasised guns over torpedoes. The ships were built in three flotilla

Flotilla

A flotilla , or naval flotilla, is a formation of small warships that may be part of a larger fleet. A flotilla is usually composed of a homogeneous group of the same class of warship, such as frigates, destroyers, torpedo boats, submarines, gunboats, or minesweepers...

s or groups, eight each of ships with names beginning with "J", "K" and "N". The flag superior of the pennant number

Pennant number

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

s changed from "F" to "G" in 1940.

Design history

The design was intended as a smaller follow on from the preceding Tribal class, and incorporated one radical new idea that was a departure from all previous Royal Navy destroyer designs. That was the adoption of a two boiler room layout. This reduced hull length and allowed for a single funnel, both reducing the profile and increasing the arcs of fire of the light Anti-aircraft (A/A) weapons

Anti-aircraft warfare

NATO defines air defence as "all measures designed to nullify or reduce the effectiveness of hostile air action." They include ground and air based weapon systems, associated sensor systems, command and control arrangements and passive measures. It may be to protect naval, ground and air forces...

. However, this also increased vulnerability, as there were now two consecutive large compartments with the resultant risk of a single well placed hit flooding both and resulting in a total loss of boiler power. This illustrates somewhat the Admiralty's attitude to the expendable nature of destroyers.

A significant advance in construction techniques was developed by naval architect Albert Percy Cole. Instead of going for transverse frame sections being unnecessarily strong, held together by weak longitudinals, Cole went for extra strong longitudinals and weaker transverse frames.

Another advancement was changes to the bow design. The bow form was also modified from that of the preceding Tribal class design; the clipper bow replaced by a straight stem with increased sheer. This change was not a success and as a consequence these ships were very wet forwards. This shortcoming was rectified from the S class

S and T class destroyer

The S and T class was a class of sixteen destroyers of the Royal Navy launched in 1942–1943. They were built as two flotillas, known as the 5th and 6th Emergency Flotilla respectively and they served as fleet and convoy escorts in World War II.-Design features:The S class, introduced the CP ...

 onwards by returning to the earlier form.

Despite the vulnerability of the boiler layout, the design was to prove compact, strong and very successful, forming the basis of all Royal Navy destroyer construction from the O class

O and P class destroyer

The O and P class was a class of destroyers of the British Royal Navy. Ordered in 1939, they were the first ships in the War Emergency Programme, also known as the 1st and 2nd Emergency Flotilla, respectively...

 up to the Cr class of 1944.

The armament was based on that of the Tribals, but replaced one twin 4.7 in (119.4 mm) QF Mark XII

4.7 inch QF Mark XII

The 4.7 inch QF Mark IX and Mark XII were 120-mm 45-calibre naval guns which armed the majority of Royal Navy and Commonwealth destroyers in World War II, and were exported to many countries after World War II as the destroyers they were mounted on were sold off.-Description and history:These guns...

 (L/45) gun on mounting CP Mk.XIX with an additional bank of torpedo tubes. These mountings were capable of 40° elevation and 340° of training. Curiously, 'X' mounting was shipped so that the blind 20° arc was across the stern, rather than the more logical forward position where fire was obscured by the bridge and masts anyway. This meant that they were unable to fire dead astern. With the tubes now pentad, a heavy load of 10 torpedoes Mk.IX were now carried. The A/A armament remained the same, consisting of a quadruple QF 2 pdr gun Mark VIII

QF 2 pounder naval gun

The 2-pounder gun, officially designated the QF 2-pounder and universally known as the pom-pom, was a 1.575 inch British autocannon, used famously as an anti-aircraft gun by the Royal Navy. The name came from the sound that the original models make when firing...

 on mounting Mk.VII and a pair of quadruple 0.5 in Vickers machine guns

Vickers machine gun

Not to be confused with the Vickers light machine gunThe Vickers machine gun or Vickers gun is a name primarily used to refer to the water-cooled .303 inch machine gun produced by Vickers Limited, originally for the British Army...

, and was later improved by the replacing the quadruple machine guns with 20mm Oerlikons. These ships, when completed, had a comparatively heavy close range AA armament. Fire control arrangements also differed from the Tribals, and the dedicated high-angle (H/A) rangefinder

Coincidence rangefinder

A coincidence rangefinder is a type of rangefinder that uses mechanical and optical principles to allow an operator to determine the distance to a visible object....

 director was not fitted, instead only a 12 ft (3.7 m) rangefinder was carried behind the usual destroyer director control tower (DCT). In the event, the rangefinder was heavily modified to allow it to control the main armament for A/A fire, and was known as the "3 man modified rangefinder". These ships used the Fuze Keeping Clock

Fuze Keeping Clock

The Fuze Keeping Clock was a simplified version of the Royal Navy's High Angle Control System analogue fire control computer. It first appeared as the FKC Mk1 in destroyers of the 1938 Tribal class, while later variants were used on sloops, frigates, destroyers, aircraft carriers and several...

 HA Fire Control Computer.

The N class were ordered in 1940 as repeats of the J design, after delays and cost over-runs associated with the larger and more complicated L and M class

L and M class destroyer

The L and M class was a class of sixteen destroyers which served in the British Royal Navy during World War II. The ships of the class were launched between 1939 and 1942.-Design details:...

. The only design change was to mount the 'X' 4.7-in mounting in the more logical position with the 20° training blindspot forward. While building, the same early wartime modifications as the Js and Ks were applied, with a pair of twin power-operated 0.5 in machine gun turrets briefly carried on the quarterdeck

Quarterdeck

The quarterdeck is that part of a warship designated by the commanding officer for official and ceremonial functions. In port, the quarterdeck is the most important place on the ship, and is the central control point for all its major activities. Underway, its importance diminishes as control of...

 before being replaced by single 20 mm Oerlikons.

Modifications

In 1940 and 1941, to improve the anti-aircraft capabilities, all ships had their aft torpedo tubes removed and replaced with a single 4 inch gun QF Mark V

QF 4 inch Mk V naval gun

The QF 4 inch Mk V gun was a Royal Navy gun of World War I which was adapted on HA mountings to the heavy anti-aircraft role both at sea and on land, and was also used as a coast defence gun.-Naval service:...

 on mounting HA Mark III. The relatively ineffective multiple 0.5 inches (12.7 mm) machine guns were replaced with single 20 mm Oerlikon guns

Oerlikon 20 mm cannon

The Oerlikon 20 mm cannon is a series of autocannons, based on an original design by Reinhold Becker of Germany, very early in World War I, and widely produced by Oerlikon Contraves and others...

, with a further pair added abreast the searchlight platform amidships. The high-speed destroyer mine sweeps

Minesweeper (ship)

A minesweeper is a small naval warship designed to counter the threat posed by naval mines. Minesweepers generally detect then neutralize mines in advance of other naval operations.-History:...

 were replaced with a rack and two throwers for 45 depth charges and Radar Type 286 air warning was added at the masthead alongside Type 285 fire control on the H/A rangefinder-director.

In 1942 the 4 in gun was removed and the torpedoes returned to all surviving vessels. The 20 mm Oerlikon guns were replaced with twin mountings (except those on the quarterdeck) and Radar Type 291 replaced the Type 286. Jervis, Kelvin, Nerissa and Norman had the searchlight replaced with the "lantern" for centimetric target indication Radar Type 271; Javelin and Kimberley having the lighter Type 272 fitted at the truck of the foremast. Napier, Nizam and Norseman (and later, Norman) had American Radar SG1 fitted at the head of a new lattice foremast, Norman replacing her Type 271 set with a single 40 mm Bofors gun. By the end of the war, the surviving J and K ships carried a lattice mast with Radar Type 293 target indication at the truck and Type 291 air warning at the head.

Service

Being amongst the Royal Navy's most modern and powerful destroyers at the outbreak of war, they were heavily committed. As a result, losses were heavy and of 24 ships built, six J, six K and one N class were war losses.

J class

Pennant number Pennant number In the modern Royal Navy, and other navies of Europe and the Commonwealth, ships are identified by pennant numbers...	Name	Builder	Laid down	Launched	Completed	Fate
F00	Jervis HMS Jervis (F00) HMS Jervis was a J-class destroyer of the Royal Navy named after Admiral John Jervis . Jervis was laid down by R. and W. Hawthorn, Leslie and Company, Limited, at Hebburn-on-Tyne on 26 August 1937...  ‡	Hawthorn Leslie & Company, Hebburn Hebburn Hebburn is a small town situated on the south bank of the River Tyne in North East England, sandwiched between the towns of Jarrow and Bill Quay...	26 August 1937	9 September 1938	12 May 1939	Sold for scrapping 1949
F22	Jackal HMS Jackal (F22) HMS Jackal was a J-class destroyer of the Royal Navy laid down by John Brown and Company, Limited, at Clydebank in Scotland on 24 September 1937, launched on 25 October 1938 and commissioned on 31 March 1939...	John Brown & Company John Brown & Company John Brown and Company of Clydebank was a pre-eminent Scottish marine engineering and shipbuilding firm, responsible for building many notable and world-famous ships, such as the , the , the , the , the , and the... , Clydebank Clydebank Clydebank is a town in West Dunbartonshire, in the Central Lowlands of Scotland. Situated on the north bank of the River Clyde, Clydebank borders Dumbarton, the town with which it was combined to form West Dunbartonshire, as well as the town of Milngavie in East Dunbartonshire, and the Yoker and...	24 September 1937	25 October 1938	31 March 1939	Bombed off Mersa Matruh on 11 May 1942 and scuttled by Jervis following day.
F34	Jaguar HMS Jaguar (F34) HMS Jaguar was a J class destroyer of the Royal Navy laid down by William Denny, Brothers and Company, Limited, of Dumbarton in Scotland on 25 November 1937, launched on 22 November 1938 and commissioned on 12 September 1939...	William Denny & Brothers, Dumbarton	1937-11-25	1938-11-22	1939-09-12	Torpedoed by German Nazi Germany Nazi Germany , also known as the Third Reich , but officially called German Reich from 1933 to 1943 and Greater German Reich from 26 June 1943 onward, is the name commonly used to refer to the state of Germany from 1933 to 1945, when it was a totalitarian dictatorship ruled by...  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.652 off Sollum, 26 March 1942
F46	Juno HMS Juno (F46) HMS Juno was a J class destroyer of the Royal Navy laid down by the Fairfield Shipbuilding and Engineering Company, Limited, at Govan in Scotland on 5 October 1937, launched on 8 December 1938 and commissioned on 25 August 1939. Juno participated in the Battle of Calabria in July 1940 and the... (ex-Jamaica)	Fairfield Shipbuilding & Engineering Company, 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....	1937-10-15	1938-12-08	1939-08-25	Bombed and sunk south of Crete Crete Crete is the largest and most populous of the Greek islands, the fifth largest island in the Mediterranean Sea, and one of the thirteen administrative regions of Greece. It forms a significant part of the economy and cultural heritage of Greece while retaining its own local cultural traits... , 21 May 1941
F53	Janus HMS Janus (F53) HMS Janus , named after the Roman god, was a J-class destroyer of the Royal Navy laid down by Swan Hunter & Wigham Richardson Limited at Wallsend-on-Tyne on 29 September 1937, launched on 10 November 1938 and commissioned on 5 August 1939. Janus participated in the Battle of Calabria in July 1940...	Swan Hunter & Wigham Richardson, Wallsend Wallsend Wallsend is an area in North Tyneside, Tyne and Wear, England. Wallsend derives its name as the location of the end of Hadrian's Wall. It has a population of 42,842.-Romans:...	29 September 1937	11 October 1938	5 August 1939	Torpedoed and sunk off Anzio Anzio Anzio is a city and comune on the coast of the Lazio region of Italy, about south of Rome.Well known for its seaside harbour setting, it is a fishing port and a departure point for ferries and hydroplanes to the Pontine Islands of Ponza, Palmarola and Ventotene...  by German aircraft, 23 January 1944
F61	Javelin HMS Javelin (F61) HMS Javelin was a J-class destroyer of the Royal Navy laid down by John Brown and Company, Limited, at Clydebank in Scotland on 11 October 1937, launched on 21 December 1938, and commissioned on 10 June 1939.... (ex-Kashmir)	John Brown	11 October 1937	21 December 1938	10 June 1939	Sold for scrapping 1949
F72	Jersey HMS Jersey (F72) HMS Jersey was a J-class destroyer of the Royal Navy laid down by J. Samuel White and Company at Cowes on the Isle of Wight on 20 September 1937, launched on 26 September 1938 and commissioned on 28 April 1939...	J. Samuel White J. Samuel White J. Samuel White was a British shipbuilding firm based in Cowes, taking its name from John Samuel White . It came to prominence during the Victorian era... , Cowes Cowes Cowes is an English seaport town and civil parish on the Isle of Wight. Cowes is located on the west bank of the estuary of the River Medina facing the smaller town of East Cowes on the east Bank...	1937	26 September 1938	28 April 1939	Mined off Valetta 2 May 1941, broke in two and sank 2 days later
F85	Jupiter HMS Jupiter (F85) HMS Jupiter was a J-class destroyer of the Royal Navy laid down by Yarrow & Company at Scotstoun in Glasgow on 28 September 1937, launched on 27 October 1938 and commissioned on 25 June 1939.-Operations:...	Yarrow & Company, Scotstoun Scotstoun Scotstoun is a historic district of Glasgow, Scotland, west of Glasgow City Centre. It is bounded by Yoker and Knightswood to the west, Victoria Park, Broomhill and Whiteinch to the east, Jordanhill to the north and the River Clyde to the south...	28 September 1937	27 October 1938	25 June 1939	Hit a Dutch mine during the battle of the Java Sea Battle of the Java Sea The Battle of the Java Sea was a decisive naval battle of the Pacific campaign of World War II, that sealed the fate of the Netherlands East Indies....  27 February 1942 and sank following day
-	Jubilant	-	-	-	-	Ordered March 1937, cancelled December 1937

K class

Pennant number	Name	Builder	Laid down	Launched	Completed	Fate
F01	Kelly HMS Kelly (F01) HMS Kelly was a K-class destroyer of the British Royal Navy, and flotilla leader of her class. She served through the early years of the Second World War; in Home Waters, off Norway and in the Mediterranean. Throughout her service, Kelly was commanded by Lord Louis Mountbatten. She was lost in...  ‡	Hawthorn Leslie	26 August 1937	25 October 1938	23 August 1939	Bombed by German aircraft and sunk south of Crete, 23 May 1941
F28	Kandahar HMS Kandahar (F28) HMS Kandahar was a K-class destroyer of the Royal Navy, named after the Afghan city of Kandahar.-History:Kandahar was launched on 21 March 1939. On 21 February 1941, in company with and , she captured the German blockade runner off Iceland...	Denny	1938-01-18	1939-03-21	1939-10-10	Mined off Tripoli Tripoli Tripoli is the capital and largest city in Libya. It is also known as Western Tripoli , to distinguish it from Tripoli, Lebanon. It is affectionately called The Mermaid of the Mediterranean , describing its turquoise waters and its whitewashed buildings. Tripoli is a Greek name that means "Three...  19 December 1941 and sunk by gunfire from Jaguar following day
F12	Kashmir HMS Kashmir (F12) HMS Kashmir was a K-class destroyer of the Royal Navy laid down by Thornycroft in Southampton in October 1937, launched on 4 April 1939 and commissioned on 26 October 1939.... (ex-Javelin)	John I. Thornycroft & Company John I. Thornycroft & Company John I. Thornycroft & Company Limited, usually known simply as Thornycroft was a British shipbuilding firm started by John Isaac Thornycroft in the 19th century.-History:... , Woolston	1937-11-18	1939-04-04	1939-10-26	Bombed by German aircraft and sunk south of Crete, 23 May 1941
F37	Kelvin HMS Kelvin (F37) HMS Kelvin was a K-class destroyer of the Royal Navy laid down by the Fairfield Shipbuilding and Engineering Company, Limited, at Govan in Scotland on 5 October 1937, launched on 19 January 1939 and commissioned on 27 November 1939....	Fairfield	1937-10-05	1939-01-19	1939-11-27	Sold for scrapping 1949
F45	Khartoum HMS Khartoum (F45) HMS Khartoum was a K-class destroyer of the Royal Navy, ostensibly named after the capital of Sudan, Khartoum.-History:Khartoum was launched on 6 February 1939. Her initial action occurred on 19 December 1939, during deployment in the Firth of Clyde, when she was subject to an unsuccessful torpedo...	Swan Hunter	1937-10-27	1939-02-06	1939-11-06	Sank in Perim Perim Perim is a volcanic island strategically located in the Strait of Mandeb at the southern entrance into the Red Sea, off the southwestern coast of Yemen, at . It has a surface area of 13 square kilometers and rises to an altitude of 65 meters. The island has a natural harbour on its southwestern...  Harbour after an exploding torpedo air vessel set off a fire which reached the aft magazine. 1940-06-23
F50	Kimberley HMS Kimberley (F50) HMS Kimberley was a K-class destroyer of the Royal Navy. She served in the Second World War and survived it, being one of only two of the K-class to do so. So far she has been the only ship of the Royal Navy to bear the name Kimberley, after the town of Kimberley, Northern Cape, site of the Siege...	Thornycroft	1938-01-17	1939-06-01	1940-02-21	Sold for scrapping 1949
F64	Kingston HMS Kingston (F64) HMS Kingston was a K-class destroyer of the Royal Navy laid down by J. Samuel White and Company at Cowes on the Isle of Wight on 6 October 1937 as part of an order for six similar destroyers....	White	1937-10-06	1939-01-09	1939-09-14	Seriously damaged by the Italian battleship Littorio Italian battleship Littorio |-External links:...  during the Second Battle of Sirte Second Battle of Sirte The Second Battle of Sirte was a naval engagement in which the escorting warships of a British convoy to Malta frustrated a much more powerful Regia Marina squadron. The British convoy was composed of four merchant ships escorted by four light cruisers, one anti-aircraft cruiser, and 17 destroyers... , 22 March 1942. Later (11 April 1942) bombed by German aircraft while in dry dock in Valletta and written off as constructive total loss. Expended as blockship off Malta
F91	Kipling HMS Kipling (F91) HMS Kipling was a K-class destroyer of the Royal Navy laid down by Yarrow, Scotstoun on 20 October 1937, launched on 19 January 1939, by the daughter of the poet Rudyard Kipling, and commissioned on 12 December 1939. On 28 December 1941 Kipling sank the German submarine U-75...	Yarrow	26 October 1937	19 January 1939	22 December 1939	Bombed and sunk by German aircraft off Mersa Matruh, 11 May 1942

N class

Those N class of the Royal Australian Navy were manned by, and commissioned into, that force, but remained the property of the British Government.

Pennant number	Name	Builder	Laid down	Launched	Completed	Fate
G84	Noble	Denny	10 July 1939	17 April 1941	20 February 1942	To the Netherlands as Van Galen HNLMS Van Galen (G84) HNLMS Van Galen was an N-class destroyer for the Royal Netherlands Navy during World War II. Built as the British Royal Navy destroyer HMS Noble , but was commissioned into the Royal Netherlands Navy shortly after completion...  1942, sold for scrapping 1957
G16	Nonpareil	Denny	1940-05-22	1941-06-25	1942-10-30	To Netherlands as Tjerk Hiddes 1942. To Indonesia Indonesian Navy The role of the Indonesian Navy is to patrol of Indonesia's immense coastline, to ensure safeguard the territorial waters and Exclusive Economic Zone , to protect Indonesia's maritime strategic interests, to protect the islands surrounded Indonesia and to defend against seaborne threats. The TNI...  as Gadjah Mada 1951, sold for scrapping 1961
G97	Napier HMAS Napier (G97) HMAS Napier was an N class destroyer serving in the Royal Australian Navy during World War II. Built During 1939 and 1940, the destroyer was commissioned into the RAN, although she was ordered and owned by the British government...  ‡	Fairfield	1939-07-26	1940-05-22	1940-12-11	Sold for scrapping 1945
G02	Nestor HMAS Nestor (G02) HMAS Nestor was an N class destroyer of the Royal Australian Navy . Built in Scotland, Nestor was commissioned in February 1941; although manned by Australians and commissioned as an Australian warship, she remained the property of the Royal Navy.Entering service in 1941, Nestor spent most of her...	Fairfield	1939-07-26	1940-07-09	1941-02-12	Bombed by Italian aircraft 15 June 1942 and sunk by depth charges from Javelin
G38	Nizam HMAS Nizam (G38) HMAS Nizam was an N class destroyer of the Royal Australian Navy . The destroyer, named after Sir Osman Ali Khan, The Last Nizam of Hyderabad, was commissioned into the RAN in 1940, although the ship remained the property of the Royal Navy for her entire career.Nizam spent the early part of her...	John Brown	1939-07-27	1940-07-04	1940-12-19	Sold for scrapping 1955
G49	Norman HMAS Norman (G49) HMAS Norman was an N class operated by the Royal Australian Navy during World War II. Entering service in 1941, the ship was on loan from the Royal Navy....	Thornycroft	1939-07-27	1940-10-30	1941-09-29	Sold for scrapping 1958
G25	Nepal HMAS Nepal (G25) HMAS Nepal was an N class destroyer of the Royal Australian Navy . Launched in 1941 as Noreseman, the ship suffered significant damage during an air raid on the John I. Thornycroft and Company shipyard, and during repairs was renamed to recognise Nepal's contribution to the British war effort... (ex-Norseman)	Thornycroft	1939-09-09	1941-12-04	1942-05-29	Sold for scrapping 1955
G65	Nerissa	John Brown	26 July 1939	7 May 1940	12 February 1941	To Poland as Piorun ORP Piorun (G65) ORP Piorun was an used by the Polish Navy during the Second World War. The name is Polish for "Thunderbolt".-History:The ship was built by John Brown & Company of Clydebank, Glasgow. She was laid down in July 1939, launched on 7 May 1940 and completed on 4 November 1940... 1940, returned as HMS Noble 1946, sold for scrapping 1955

External links