page_title: Armstrong Whitworth 12-inch 40-calibre naval gun
section_title: Royal Navy service
hierarchical_section_title: Armstrong Whitworth 12-inch 40-calibre naval gun / United Kingdom service / Royal Navy service
caption_attribution_description: Photograph showing forward 12 inch Mk IX guns of British battleship HMS Queen. The is a clip from File:HMS Queen.jpg
context_page_description: The Armstrong Whitworth 12-inch naval gun of 40 calibres length was designed by and manufactured mainly by Armstrong's ordnance branch, Elswick Ordnance Company. It was intended for the Royal Navy's Royal Sovereign-class battleships, but budgetary constraints delayed their introduction. The first units were instead supplied to Japan. As the Type 41 12-inch 40-calibre naval gun it was the standard main battery on several early United Kingdom-built pre-dreadnought battleships of the Imperial Japanese Navy.
  It later entered service with the RN as the 12-inch Mark IX, being fitted to warships of three pre-dreadnought classes prior to World War I. Also, during the war several guns were converted for use as railway guns, and, towards the end of the conflict, for use on the M-class submarine monitors.
  The gun also saw service with the Italian Regia Marina, in two classes of pre-dreadnought battleships.
context_section_description: The gun entered service with the Royal Navy as "BL 12 inch gun Mark IX" on the following ships :
  Formidable-class battleships: Three ships, laid down 1898 and mounting four guns each.
  London-class battleships: Five ships, laid down in 1898–1901 and mounting four guns each.
  Duncan-class battleships: Six ships laid down 1899, each mounting four guns.
  King Edward VII-class battleships of 1904. Five of the eight ships of this class (HMS King Edward VII, HMS Commonwealth, HMS Hindustan, HMS Dominion and HMS New Zealand) carried the Mark IX gun.
caption: Forward guns of HMS Queen
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