The QF 4.5 inch gun has been the standard medium-calibre naval gun used by the Royal Navy as a medium-range weapon capable of use against surface, aircraft and shore targets since 1938. This article covers the early 45-calibre family of guns up to the 1970s. For the later unrelated 55-calibre Royal Navy gun, see 4.5 inch Mark 8 naval gun. Like all British nominally 4.5 inch naval guns, the QF Mk I has an actual calibre of 4.45 inches (113 mm).
The Arethusa-class cruisers were a class of eight oil-fired light cruisers of the Royal Navy all ordered in September 1912, primarily for service in the North Sea. They had three funnels with the middle one somewhat larger in diameter than the others. All served in the First World War. They were found to be very cramped internally.
HMS Arethusa was the name ship of her class of eight light cruisers built for the Royal Navy in the 1910s. She saw a considerable amount of action during the early years of the First World War, participating in the Battle of Heligoland Bight and the Battle of Dogger Bank.
The BL 6-inch gun Mark VII was a British naval gun dating from 1899, which was mounted on a heavy travelling carriage in 1915 for British Army service to become one of the main heavy field guns in the First World War, and also served as one of the main coast defence guns throughout the British Empire until the 1950s.
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 1880s and 1890s that 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. They all had a barrel of 40 calibres length.
HMS Penelope was one of eight Arethusa-class light cruisers built for the Royal Navy in the 1910s. She fought in the First World War, following the war, she was scrapped.
HMS Undaunted was one of eight Arethusa-class light cruisers built for the Royal Navy in the 1910s.
The Active-class cruisers were a trio of scout cruisers built for the Royal Navy shortly before the First World War. They were initially assigned to the First Fleet and became destroyer flotilla leaders in 1914. Amphion and Fearless and their flotillas were assigned to the Harwich Force when the war began in August 1914. They went out on a patrol on the first day of the war and Amphion and her destroyers encountered and sank a German minelayer. On the voyage home, the cruiser struck a mine laid by the German ship and sank. She was the first ship of the Royal Navy to be sunk in the war.
The QF 6-inch 40 calibre naval gun (Quick-Firing) was used by many United Kingdom-built warships around the end of the 19th century and the start of the 20th century. In British service it was known as the QF 6-inch Mk I, II, III guns. As the 15 cm/40 (6") 41st Year Type naval gun it was used for pre-dreadnought battleships, armoured cruisers and protected cruisers of the early Imperial Japanese Navy built in UK and European shipyards. It was also the heaviest gun ever carried by a pre-Cold War destroyer.
The Ordnance QF Hotchkiss 6 pounder gun Mk I and Mk II or QF 6 pounder 8 cwt were a family of long-lived light 57 mm naval guns introduced in 1885 to defend against new, small and fast vessels such as torpedo boats and later submarines. There were many variants produced, often under license which ranged in length from 40 to 58 calibers, but 40 caliber was the most common version.
The QF 3-pounder Hotchkiss or in French use Canon Hotchkiss à tir rapide de 47 mm were a family of long-lived light 47 mm naval guns introduced in 1886 to defend against new, small and fast vessels such as torpedo boats and later submarines. There were many variants produced, often under license which ranged in length from 32 to 50 calibers but 40 caliber was the most common version. They were widely used by the navies of a number of nations and often used by both sides in a conflict. They were also used ashore as coastal defense guns and later as an anti-aircraft gun, whether on improvised or specialized HA/LA mounts.
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.
The QF 4 inch Mk XVI gun was the standard British Commonwealth naval anti-aircraft and dual-purpose gun of World War II.
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.
The BL 4-inch gun Mk VII was a British high-velocity naval gun introduced in 1908 as an anti-torpedo boat gun in large ships, and in the main armament of smaller ships. Of the 600 produced, 482 were still available in 1939 for use as coastal artillery and as a defensive weapon on Defensively Equipped Merchant Ships (DEMS) during the Second World War.
The BL 4-inch Mark VIII naval gun 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.
The BL 6-inch Mark XII naval gun was a British 45 calibre naval gun which was mounted as primary armament on light cruisers and secondary armament on dreadnought battleships commissioned in the period 1914–1926, and remained in service on many warships until the end of World War II.
The 4.7 inch QF Mark IX and Mark XII were 45-calibre, 4.7-inch (120 mm) 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.
