EOC 12-inch 45-calibre naval gun

The EOC 12 inch 45 calibre gun were various similar 12-inch wire-wound naval guns designed and manufactured by Elswick Ordnance Company to equip ships that the parent company Armstrong Whitworth built and/or armed for several countries before World War I.

Brazil service
Elswick supplied its 12-inch 45-calibre guns for the Minas Geraes-class battleships completed by itself and Vickers in 1910 for Brazil.

UK service
When World War I began, Elswick were completing the battleship OTTOMAN BATTLESHIP Sultân Osmân-ı Evvel for the Ottoman Empire, originally begun as BRAZILIAN BATTLESHIP Rio de Janeiro for Brazil. It was armed with 14 of a slightly later version of Elswick's 12-inch 45-calibre guns. The battleship was completed as HMS Agincourt (1913) and served in the Royal Navy in World War I, with its guns designated BL 12 inch Mk XIII. The gun's performance was similar to the standard Royal Navy equivalent gun, the BL 12 inch Mk X designed by Vickers.

Japan service
Elswick supplied its 12-inch 45-calibre guns to the Imperial Japanese Navy, and they were also manufactured under licence in Japan. In Japanese service from 1908 they became 12"/45 41st Year Type and later after the navy metricised in 1917, 30 cm/45 41st Year Type. They equipped the following ship classes:
 * Katori-class battleships commissioned 1906
 * Ibuki-class battlecruiser commissioned in 1907 & 1911
 * Tsukuba-class cruiser battlecruisers commissioned 1908
 * Battleship JAPANESE BATTLESHIP Mikasa as re-gunned in 1908
 * Satsuma-class battleships commissioned 1910 & 1912
 * Kawachi-class battleships commissioned 1912

Surviving examples

 * On the JAPANESE BATTLESHIP Mikasa, Yokosuka, Japan

Weapons of comparable role, performance and era

 * 305mm/45 Modèle 1906 gun French equivalent
 * BL 12 inch Mk X naval gun Vickers equivalent
 * 12"/45 caliber Mark 5 gun US equivalent