The QF 4.7 inch Gun Mks I, II, III, and IV were a family of British quick-firing 4.724-inch (120 mm) naval and coast defence guns of the late 1880's and 1890's which served with the navies of various countries. They were also mounted on various wheeled carriages to provide the British Army with a long range gun.
The guns were designed and manufactured by the Elswick Ordnance Company, part of Armstrong Whitworth. They were a major export item and hence were actually of 4.724 inches to meet the requirements of metricised navies: 4.7 inch is an approximation used for the British designation. The guns, Mark I to Mark III, were Pattern P, Pattern Q and Pattern T respectively. All three differed in detail of construction but were of the tube and hoop types. The Mark IV differed from these by incorporating a wire wound element to its construction. As first built, all used a three-motion screw breech, some were altered later by modifying the three-motion screw becoming "A" subtypes, or by fitting a single motion breech ("B" type). Army guns altered to use a bagged charge with a 3-inch steel (instead of the more usual brass) breech-sealing case, and were renumbered as Mark VI.
They all had a bore of 40 calibres length. Their rate of fire was 5 to 6 rounds per minute; with a muzzle velocity of 1,786 feet per second (544 m/s) using gunpowder and 2,150 feet per second (660 m/s) using cordite. Maximum firing range was 10,000 yards (9,100 m) at 20°, and 12,000 yards (11,000 m) at 24°. It required a crew of ten to fire it.
The naval version was used by the Australian Colonial Navies, the United Kingdom, Italy, Japan and Canada. The armies of Australia, the United Kingdom, Canada, and South Africa used it; and it was mounted on shore for coast defence by the United Kingdom, the United States and Canada.
British pre-dreadnoughts and cruisers of the period used these guns. Total production was 154 Mark I, 91 Mark II, 338 Mark III and 584 Mark IV. The Royal Navy received 776 of these guns directly, and the Army later transferred a further 110 to the Navy. The Latona-class minelayer gave up their guns to produce high-angle anti-aircraft guns to defend London, but by World War I the guns were mostly obsolete for warship use; however, many were re-mounted on merchant ships and troopships for defence against enemy submarines and commerce raiders.
British Army service - Some Mark IV guns were mounted on converted 40-Pr Rifled Breech Loading Gun carriages for use by batteries of the Volunteer Artillery. These were semi-mobile guns with limbers, which could be drawn by horses or gun tractors. They continued in use with artillery units of the Territorial Force, with some being used in the Second Boer War (1899–1902), where British forces were initially outgunned by the long range Boer artillery. Captain Percy Scott of HMS Terrible first improvised static timber siege mountings for two 4.7-inch guns from the Cape Town coastal defenses, to counter the Boers' "Long Tom" gun during the Siege of Ladysmith in 1899–1900. Captain Scott then improvised a travelling carriage for 4.7 inch guns to provide the army with a heavy field gun. These improvised carriages lacked recoil buffers, and hence in action drag shoes the and attachment of the carriage by cable to a strong point in front of the gun was necessary to control the recoil. They were manned by Royal Navy crews and required up to 32 oxen to move.
During World War I, in the South-West Africa Campaign (1914–1915), the same guns mounted on "Percy Scott" carriages were used by South African forces against German forces. Guns were landed at Lüderitz Bay in October 1914 and later at Walvis Bay in February 1915 and moved inland across the desert in support of South African troops. In the Western Front (1914–1917) up to 92 QF 4.7 inch guns on more modern Mk I "Woolwich" carriages that had partially effective (12 inch) recoil buffers, and on heavier "converted" carriages from old RML 40 pounder guns, went to France, mostly of the Territorial Force, in 1914–1917. They figured prominently in the early battles, such as at Neuve Chapelle in March 1915. By the Battle of Aubers Ridge on 9 May 1915 the barrels of the 28 guns of the 3rd and 8th Heavy Brigades and the 1st West Riding and 1st Highland Heavy Batteries were now so worn that driving bands were stripped off shells at the muzzle, limiting their accuracy. The inaccuracy through wear and relatively light shell diminished their usefulness, and they were replaced by the modern 60-pounder guns as they became available. At the Battle of the Somme in June–July 1916 there were 32 4.7-inch guns and 128 60-pounders engaged. The last were however not withdrawn until April 1917. Guns withdrawn from the Western Front were redeployed to other fronts such as Italy and Serbia.
Battle of Gallipoli (1915) - A 4.7 inch gun was used by the 1st Heavy Artillery Battery, a joint unit of Australians and Royal Marines, on Gallipoli to counter long range Turkish fire from the "Olive Grove" (in fact "Palamut Luk" or Oak Grove) between Gaba Tepe and Maidos. Lt-Colonel Rosenthal, commanding 3rd Australian Field Artillery Brigade, noted : "I had made continual urgent representations for two 4.7-inch guns for right flank to deal with innumerable targets beyond the range of 18-prs., but it was not till 11 July that one very old and much worn gun arrived, and was placed in position on right flank, firing its first round on 26 July." This gun was destroyed and left behind at the withdrawal from Gallipoli but later salvaged as a museum piece. The burst barrel is on display at the Australian War Memorial.