page_title: BL 18-inch Mk I naval gun
section_title: Service
hierarchical_section_title: BL 18-inch Mk I naval gun / Service
caption_attribution_description: English: The Surrender of the German High Seas Fleet, November 1918 The 18-inch gun of HMS Lord Clive at full elevation
context_page_description: The BL 18-inch Mk I naval gun was a breech-loading naval rifle used by the Royal Navy during World War I. It was the largest and heaviest gun ever used by the British. Only the Second-World-War Japanese 40 cm/45 Type 94 had a larger calibre, 18.1 inches, but the British shell was heavier. The gun was a scaled-up version of the BL 15 inch Mk I naval gun and was developed to equip the "large light cruiser" Furious. Its barrel length of 60' was just 40 calibers, slightly limiting its muzzle velocity.
  Only three guns were built, but they did not see combat with Furious before they were removed from her and transferred to the Lord Clive-class monitors General Wolfe and Lord Clive for coast bombardment duties. Only 85 rounds were fired in combat operations before the war ended. All three were removed from service in 1920 and served as proving guns for cordite tests. Two were scrapped in 1933 and the last one survived until it was scrapped in 1947.
context_section_description: A total of three guns were built by Armstrong Whitworth, two for Furious and a spare. The forward gun was removed from Furious in March 1917, before she was completed, when she was ordered to be converted to a seaplane carrier. The second gun was removed later in 1917, and she was converted into an aircraft carrier. The new 'B CD' mounts were delayed, and the mount for Lord Clive-class monitor General Wolfe was not delivered until 20 June 1918. The gun from Furious' 'A' turret was lifted aboard on 9 July, but the General Wolfe was not ready to begin firing trials until 7 August. She was given the nickname of 'Elephant and Castle', as the enormous gun-mount structure dominated the ship's profile.
  While the new mounting was being designed, further effort was put into the ammunition to extend the range as much as possible. Use of a supercharge, where one of the six charges was increased in weight to 165 pounds (74.8 kg), making a total of 690 pounds (313.0 kg) propellant, and increasing the elevation to 45° extended the range to about 36,900 yards (33,700 m) with the existing 4 crh shells. New 8 crh high explosive shells, with a longer, thinner ballistic cap, were ordered, but only two shells had been delivered before the end of the war. Some of the existing stock of 500 APC and 500 CPC (common, pointed, capped) shells on hand from Furious were modified with the new cap and were probably the only shells used during the war.
  General Wolfe was assigned to the Dover Patrol on 15 August 1918, but did not fire on any targets until 28 September, when a large force of monitors was gathered to harass German lines of communication. She was anchored bow and stern, broadside to her target, and had difficulties dealing with the tidal currents. She opened fire on the railway bridge at Snaeskerke (4 miles (6.4 km) south of Ostend) at a range of 36,000 yards (32,918 m) and made naval history as the heaviest shell fired from the largest gun at the longest range in action to date. She fired 52 shells that day and found that the recoil from her 18–inch gun moved her sideways with her shallow hull and also caused her to roll, which slowed her rate of fire. She fired a total of 81 rounds before the end of the war.
  The second gun, Furious' spare, was mounted in Lord Clive, but she was not ready for combat until 13 October 1918. She fired three rounds the following day, but had to cease fire to avoid hitting friendly advancing troops. One round had already been loaded when the order came to cease fire so she fired it, with a reduced charge, into a minefield to seaward. A total of 85 18-inch shells were fired in action by both guns.    Wear on General Wolfe's gun was measured at about 0.37 inch after firing 161 effective full charges (EFC) - 105 rounds including proof and practice, with 57 being supercharges.  This indicates the gun would have been good for well over 300 EFC, comparable with most other British ordnance using Cordite MD.
  The third gun, from Furious' 'Y' turret, was intended for Prince Eugene, which had been modified to accept it earlier in the year, but the war ended before it was mounted, although the monitor was ordered to Portsmouth to have it fitted on 19 October. The guns were removed from the monitors in December 1920. Gun No. 1, from Furious' 'Y' turret, was lined down to 16 inches (410 mm) and used in cordite-proving tests for the BL 16-inch Mk I gun, intended for the cancelled G3 battlecruisers, and used in the Nelson-class battleships. It remained in use until 1942 and was scrapped in 1947. The other two guns were used at Shoeburyness and Yantlet artillery ranges in the Thames Estuary for similar duties; they were scrapped in 1933.
  One mount survived and was used to mount a spare BL 14-inch Mk VII gun from the battleship King George V. It was emplaced near Dover in 1940, and the combination was named "Pooh", after Winnie-the-Pooh.
caption: On board Lord Clive; her BL 18 inch gun is at its full elevation, November 1918
exif: {"Image XResolution": "300", "Image YResolution": "300", "Image ResolutionUnit": "Pixels/Inch", "Image YCbCrPositioning": "Centered", "Image Copyright": "Imperial War Museums"}