The QF 4-inch gun Mk IV was introduced in 1911 as a faster-loading light gun successor to the BL 4 inch Mk VIII gun

BL 4 inch naval gun Mk VIII

The BL 4-inch gun Mark VIII was a British medium-velocity wire-wound naval gun introduced in 1908 as an anti-torpedo boat gun in smaller ships whose decks could not support the strain of the heavier and more powerful Mk VII gun.-Mk VIII History:...

, and was the main gun on most 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...

 and British Empire

British Empire

The British Empire comprised the dominions, colonies, protectorates, mandates and other territories ruled or administered by the United Kingdom. It originated with the overseas colonies and trading posts established by England in the late 16th and early 17th centuries. At its height, it was the...

 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 in World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

.

Mk IV gun

Mk IV armed many British destroyers and some cruisers in World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

.
It was used to arm merchant ships in World War II

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...

.

The guns armed the following warships :

• Forward class scout cruisers
  Forward class cruiser
  The Forward class was a two ship class of scout cruiser serving with the Royal Navy in World War I, and consisting of the ships HMS Forward and HMS Foresight.-Design:...
  
   as re-gunned in 1911
• Sentinel class scout cruisers
  Sentinel class cruiser
  The Sentinel class was a two ship class of scout cruiser serving with the Royal Navy, and consisting of the ships HMS Sentinel and HMS Skirmisher.-History:...
  
   as re-gunned 1911-1912
• Pathfinder class scout cruisers
  Pathfinder class cruiser
  The Pathfinder class was a two ship class of scout cruiser serving with the Royal Navy in World War I, and consisting of the ships HMS Pathfinder and HMS Patrol....
  
   as re-gunned 1911-1912
• Adventure class scout cruisers
  Adventure class cruiser
  The Adventure class was a two ship class of scout cruiser serving with the Royal Navy in World War I, and consisting of the ships HMS Adventure and HMS Attentive.-Design:...
  
   as re-gunned 1911-1912
• Acasta (K) class destroyers
  Acasta class destroyer
  The Acasta class was a class of twenty destroyers built for the Royal Navy under the Naval Programme of 1911 - 1912 that saw service during World War I...
  
   of 1911
• Laforey (L) class destroyers
  Laforey class destroyer (1913)
  The Laforey class was a class of 22 torpedo boat destroyers of the Royal Navy, twenty of which were built under the Naval Programme of 1912 - 1913 and a further two under the War Emergency Programme of 1914. As such they were the last pre-war British destroyer design. All served during World War I...
  
   of 1913
• Yarrow M class destroyers
  Yarrow M class destroyer
  The Yarrow M class was a class of ten destroyers built for the Royal Navy that saw service during World War I. They were generally similar to the standard Admiralty M class, but were instead designed by the builder, Yarrow & Company. Generally, they had two instead of three shafts, as well as two...
  
   laid down 1912 - 1915
• Admiralty M class destroyer
  Admiralty M class destroyer
  The M class, more properly known as the Admiralty M class, were a class of 85 destroyers built for the Royal Navy that saw service during World War I...
  
   of 1913
• Thornycroft M class destroyers
  Thornycroft M class destroyer
  The Thornycroft M or Mastiff class were a class of six destroyers completed for the Royal Navy during 1914-16 for World War I service. They were quite different from the Admiralty-designed ships of the Admiralty M class class, although based on a basic sketch layout provided by the Admiralty from...
  
   laid down 1913 - 1915
• Hawthorn M class destroyer
  Hawthorn M class destroyer
  The Hawthorn M were a class of two destroyers built for the Royal Navy under the pre-war 1913-14 Programme for World War I service....
  
   of 1914
• Talisman class destroyers
  Talisman class destroyer
  The Talisman class were a class of destroyers that were being built for the Turkish Navy at the outbreak of World War I but were taken over in November 1914 and completed for the Royal Navy for wartime service...
  
   of 1914
• Medea class destroyers
  Medea class destroyer
  The Medea class were a class of destroyers that were being built for the Greek Navy at the outbreak of World War I and that were taken over and completed for the Royal Navy for wartime service. All were named after characters from Greek mythology as result of their Greek heritage.The Medeas were a...
  
   of 1914
• Faulknor class leaders
  Faulknor class leader
  The Faulknor class were a class of flotilla leaders that were under construction in the United Kingdom for the Chilean Navy at the outbreak of World War I. These ships were purchased by the British, taken over and completed for the Royal Navy for wartime service...
  
   of 1914
• Marksman class destroyers of 1914
• Parker class leaders of 1915
• Yarrow Later M class destroyers
  Yarrow Later M class destroyer
  The Yarrow Later M class were a class of seven destroyers built for the Royal Navy that saw service during World War I. They were based on the preceding and successful Yarrow M class with minor alterations; notably reduced beam to compensate for increased displacement and a sloping stern...
  
   of 1915
• R class destroyers
  R class destroyer (1916)
  The first R class were a class of 62 destroyers built between 1916 and 1917 for the Royal Navy. They were an improvement, specifically in the area of fuel economy, of the earlier M-class destroyers...
  
   of 1916
• S class destroyers
  S class destroyer (1916)
  The S class were a class of 67 destroyers built from 1917 for the Royal Navy. The design was based on the Admiralty modified R class and all ships had names beginning with S or T....
  
   of 1917
• Fundy class minesweeper
  Fundy class minesweeper
  The Fundy-class minesweepers were a class of four minesweepers operated by the Royal Canadian Navy during World War II.The class derives its name from the lead ship and are all named after bays in Canada. The Fundy Mineseepers were modified versions of the British "Basset" class trawler...
  
  s of 1938 (guns from decommissioned Canadian S class destroyers)

Mk XII and XXII submarine gun

The Mk XII variant was developed for arming submarines from 1918, Mk XXII was developed to arm submarines during World War II

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...

. These submarine guns fired a heavier 35-pound projectile from late 1944.
Mk XII and XXII equipped :

• L class
  British L class submarine
  The British L class submarine were originally planned under the emergency war programme as an improved version of the British E class submarine. The scale of change allowed the L class to become a separate class....
  
  
• Odin ("O") class
  Odin class submarine
  The Odin class submarine was a class of nine submarines developed and built for the Royal Navy in the 1920s. The prototype was followed by two ships originally ordered for the Royal Australian Navy, but transferred to the RN in 1931 because of the poor economic situation in Australia, and six...
  
  
• Parthian ("P") class
  Parthian class submarine
  The Parthian class submarine or P class was a class of six submarines built for the Royal Navy in the late 1920s. They were designed as long-range patrol submarines for the Far East. These ships were almost identical to the Odin class, the only difference being a different bow...
  
  
• River (or Thames) class
  River class submarine
  The River class, or Thames class were a class of submarines built for the Royal Navy.They were the last attempt by the Admiralty to produce "Fleet Submarines" that is submarines fast enough to operate as part of a fleet which at the time meant being able to manage somewhere around while surfaced...
  
  
• Grampus (or Porpoise) class
  Grampus class submarine
  The Grampus-class submarines were a group of minelaying submarines built for the Royal Navy in the late 1930s. These boats are sometimes referred to as the Porpoise class from the single prototype, HMS Porpoise built in 1932. Five boats to a modified design were built between 1936 and 1938...
  
  
• Triton ("T") class
  British T class submarine
  The Royal Navy's T class of diesel-electric submarines was designed in the 1930s to replace the O, P and R classes. Fifty-three members of the class were built just before and during the Second World War, where they played a major role in the Royal Navy's submarine operations...
  
  
• 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...
  
  
• Some of the Amphion ("A" or Acheron) class
  Amphion class submarine
  |-See also:- External links :**...
  
  

Surviving guns

• The Mk IV gun from HMS Lance
  HMS Lance (1914)
  HMS Lance was a Laforey-class destroyer of the Royal Navy. Launched a few months before the outbreak of the First World War and attached to the Harwich Force, Lance took part in several engagements during the war, including the sinking of the and the Battle off Texel...
  
   which fired the first British shot of World War I
  World War I
  World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...
  
   on 5 August 1914 is on display at the Imperial War Museum
  Imperial War Museum
  Imperial War Museum is a British national museum organisation with branches at five locations in England, three of which are in London. The museum was founded during the First World War in 1917 and intended as a record of the war effort and sacrifice of Britain and her Empire...
  
  , London.
• An unrestored gun near Stanley, Falkland Islands

External links