The Very Underrated British BL 14-inch Mk VII Naval Gun Designed For The RN In The Late 1930s

The Very Underrated British BL 14-inch Mk VII Naval Gun Designed For The RN In The Late 1930s


A 14-inch gun being removed from a Mark III quadruple turret in the Elswick Works
 The gun armed the King George V-class battleships that served very successfully during the Second World War.

The choice of caliber was chosen by the Second London Naval Treaty which put limits on the caliber size, the Washington Naval Treaty set limits on the size, armament, and number of battleships constructed by the major powers to try and prevent a naval arm’s race. They had disappointing experiences in practice with the combination of high velocity but relatively light shells in the BL 16 inch /45 naval gun carried on the Nelson-class battleships, so the RN changed to the combination of a lower velocity and a heavier shell for this weapon.

The new 14-inch Armour Piercing 1,590-pound shell had superior ballistic performance and armor-penetration compared to previous British shells thanks to improvements in design and material which had taken place since the first World War. The shell also carried a very large bursting charge of 48.5 lb which was larger than that of both the German KM 38 cm/52 SK C/34 15-inch guns of the Bismarck 16-inch Mk VI 2700 lb AP shells making it the best gun of the treaty battleships.

The choice of mounting was a mechanically complex and unique quadruple turret with each battleship having two quadruple turrets and one twin turret giving the ship a heavy broadside.
Gun crews of HMS DUKE OF YORK under the ship’s 14 inch guns at Scapa Flow after the sinking of the German battleship SCHARNHORST on 26 December 1943

In service the guns performed brilliantly but the quad turrets proved to be at first not as reliable than was hoped for. Wartime haste in building sometimes caused insufficient clearance between the rotating and fixed structure of the turret, it led to extensive arrangements to prevent flash from reaching the magazines which at first led to problems during prolonged actions. In order to bring ammunition into the turret at any degree of train, these defects were addressed quickly and improved clearances, improved mechanical linkages, and better training led to greater reliability in the quadruple turrets but in service they eventually silenced their doubters especially with the gun’s penetrative power.

On entering operational service, the turrets gained an initial reputation for unreliability, with individual guns and entire turrets jamming in action. However, it has also been argued that these jams were typically caused by errors in drill due to the rush into service, due to lack of gun crew training, the gun’s had trouble when the newly commissioned HMS Prince of Wales engaged the Bismarck in the Battle of the Denmark Strait. But the Prince of Wales hit Bismarck penetrating her armour flooding her fuel which ended Bismarck’s mission, after the battle Prince of Wales got her guns fully operational and tried to re-engage Bismarck but Bismarck would not give battle.

During the battle against Bismarck a close-range hit from a 14-inch shell fired by King George V penetrated the 13 inch-thick armour of the barbette of Bismarck’s ‘B’ turret.

This penetration caused a huge internal explosion which blew the rear face of the turret away. Underwater survey also shows that the 14-inch vertical armor of the conning tower of Bismarck was penetrated by 14-inch shells. In the Battle of North Cape, Duke of York fired 52 broadsides and of these 31 hit the Scharnhorst which was a fast and actively maneuvering target at night in bad Arctic weather, and a further 16 fell within 200 yards which was an excellent performance, even with radar-control.

GUNS VARIOUS AND CREWS. APRIL 1943. (A 15887) A Heavy gun and crew in HMS KING GEORGE V. Copyright: © IWM. Original Source:

The effects of the 14-inch shellfire on Scharnhorst quickly degraded her fighting ability, Duke of York’s first salvo put ‘A’ turret out of action; ‘B’ turret soon became destroyed also another hit penetrated the German ship’s armor, detonating in one of the boiler rooms greatly reducing the vessel’s speed. This reduction meant that the Scharnhorst could not escape the pursuit so was responsible for her eventual destruction.

The 14-inch Mark VII gun was responsible for 2 German capital ships destruction which made it arguably one of the most successful battleship’s main guns of World War II.

On display at Fort Nelson

The Very Underrated British BL 14-inch Mk VII Naval Gun Designed For The RN In The Late 1930s

Historian Harry Gillespie : Collected Works

Harry Gillespie is a writer who resides in the UK with his family. His work focuses on Naval & British history with a specific look at 20th century warfare and ships. From World War 1 to The Falkland Islands Campaign.

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The Very Underrated British BL 14-inch Mk VII Naval Gun Designed For The RN In The Late 1930s