The QF 4-inch gun Mks I, II, III were early British QF (quick-firing) naval guns originating in 1895. They all had barrels of 40 calibres length.

Naval service

The gun was intended to be a more powerful alternative to the 3-inch QF 12 pounder gun

QF 12 pounder 12 cwt naval gun

The QF 12 pounder 12 cwt gun was a common calibre naval gun introduced in 1894 and used until the middle of the 20th century. It was produced by Armstrong Whitworth, Elswick and used on Royal Navy warships, and exported to allied countries...

.

It was mounted on the following ships :

• Pelorus-class third class protected cruisers
  Pelorus class cruiser
  The Pelorus class cruiser was a "third-class" protected cruiser class of eleven Royal Navy warships designed by Sir William White , based on the earlier Pearl class cruisers. They were ordered in 1893 under the Spencer Program, and laid down 1896–1900...
  
   of 1896
• Condor-class sloops
  Condor class sloop
  The Condor class was a six-ship class of 10-gun screw steel sloops built for the Royal Navy between 1898 and 1900. Condor foundered in a gale, prompting the Royal Navy to abandon sailing rigs for its ships...
  
   of 1898
• Cadmus-class sloops
  Cadmus class sloop
  The Cadmus class was a six-ship class of 10-gun screw steel sloops built for the Royal Navy between 1900 and 1903. Most of the class survived until the 1920s, remaining on colonial stations during World War I.-Design:...
  
   of 1900
• Topaze-class third-class cruisers
  Topaze class cruiser
  The Topaze-class cruisers were a class of third-class protected cruisers. They were the last class of protected cruiser built for the Royal Navy...
  
   launched in 1903
• Invincible-class battlecruisers
  Invincible class battlecruiser
  The three Invincible class battlecruisers were built for the Royal Navy and entered service in 1908 as the world's first battlecruisers. They were the brainchild of Admiral Sir John Fisher, the man who had sponsored the construction of the world's first "all big gun" warship,...
  
   of 1906

Its 25-pound shell proved insufficiently powerful to make it much of an improvement on the 12-pounder. From 1907 onwards it was succeeded in its class on new warships by the BL 4 inch gun Mk VIII

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:...

, which fired a 31-pound shell.

Coast Defence gun

From 1906 a number of Mk III guns were transferred from the Royal Navy for use as coast defence guns around the United Kingdom, and remained until 1939.

In 1918 three guns were in service at Dover Garrison and eight at Forth Garrison.

World War I land service

On 20 September 1914 the British cruiser HMS Pegasus

HMS Pegasus (1897)

HMS Pegasus was one of 11 Pelorus-class protected cruisers ordered for the Royal Navy in 1893 under the Spencer Program and based on the earlier Pearl-class. The class were fitted with a variety of different boilers most of which were not entirely satisfactory and by 1914 four ships had been...

 was sunk by SMS Königsberg in Zanzibar harbour. Her 8 QF 4-inch Mk III guns were recovered and used ashore in the East African campaign

East African Campaign (World War I)

The East African Campaign was a series of battles and guerrilla actions which started in German East Africa and ultimately affected portions of Mozambique, Northern Rhodesia, British East Africa, Uganda, and the Belgian Congo. The campaign was effectively ended in November 1917...

. Some were used as coast defence guns at Zanzibar and Mombasa. Two guns, and from 11 February 1916, three guns, were used by 10th Heavy Battery manned by the Royal Marines, mounted on improvised field carriages and towed by Packard lorries, supported by six REO lorries carrying ammunition.

Surviving guns

• A gun from HMS Pegasus used in the WWI land campaign stands outside Fort Jesus
  Fort Jesus
  Fort Jesus is a Portuguese fort built in 1593 by order of King Philip I of Portugal , then ruler of the joint Portuguese and Spanish Kingdoms, located on Mombasa Island to guard the Old Port of Mombasa, Kenya. It was built in the shape of a man , and was given the name of Jesus...
  
   on Mombasa Island, Kenya, next to one of the 10.5-cm guns from SMS Königsberg.
• A gun from HMAS Protector
  HMAS Protector (1884)
  HMCS/HMAS Protector was a large flat-iron gunboat commissioned and purchased by the South Australian government in 1884, for the purpose of defending the local coastline against possible attacks in the aftermath of the ‘Russian scare', of 1870s...
  
   is on display outside the Elizabeth and Salisbury Navy Club in Elizabeth, South Australia.
• A gun installed in 1918 on the island of Hirta
  Hirta
  Hirta is the largest island in the St Kilda archipelago, on the western edge of Scotland. The name "Hiort" and "Hirta" have also been applied to the entire archipelago.-Geography:...
  
   in the St Kilda
  St Kilda, Scotland
  St Kilda is an isolated archipelago west-northwest of North Uist in the North Atlantic Ocean. It contains the westernmost islands of the Outer Hebrides of Scotland. The largest island is Hirta, whose sea cliffs are the highest in the United Kingdom and three other islands , were also used for...
  
  archipelago, northwest Scotland

External links

• Tony DiGiulian, British 4"/40 (10.2 cm) QF Marks I, II and III