HMS Agincourt joined the British Royal Navy as part of her growing "dreadnought" series of battleships commissioned prior to World War 1 (1914-1918). The dreadnought descriptor was created with the commissioning of the famous HMS Dreadnought of 1906, an all-big-gunned warship with steam propulsion that also incorporated a level blend of speed and protection into her design. Her arrival immediately made all existing lead battleships obsolete and forced national powers to follow in their pursuit of a modern warship. As such, pre-existing vessels became known as "predreadnoughts".
HMS Agincourt proved the only member of her class - which was typically rare in ship procurement. She was also originally ordered by the Brazilian government as "Rio de Janeiro" and constructed by Armstrong at Newcastle-Upon-Tyne with her keel was laid down on September 14th, 1911. She was launched to sea on January 22nd, 1913.
However, during the period of the ship's construction, Brazil fell into an economic downturn which limited her naval arms goals. Unable to afford the vessel, the Ottoman Empire (Turkey) moved in to secure the British warship in December 1913. It was to have carried the name of "Sultan Osman I". With the outbreak of World War 1 on the European mainland, the British government took on ownership of the vessel despite the Turks already having paid off two British-built warships. The British were leery of providing a warship to a nation that was leaning towards partnership with enemy Germany and this resulted in the warship entering service with the Royal Navy in August 1914. The event soured the Ottomans and eased their decision to officially join the Central Powers.
Named after the Battle of Agincourt, which was a decisive English victory over the hated French in October of 1415, HMS Agincourt was commissioned on August 7th and finally completed on August 20th. As built, she was a unique vessel as dreadnoughts went - fitting seven turrets and no fewer than 14 x 12" (304.8mm) BL Mk XIII guns as her main battery. The massed weight lessened her armor protection but she was able to make headway at 22 knots on full in ideal conditions and her sea keeping was regarded as sound. Her propulsion arrangement included 22 x Babcock and Wilcox water-tube boilers with 4 x Parsons steam turbines developing 34,000 horsepower to 4 x shafts which allowed a range of 8,100 miles. At the center of her profile were a pair of smoke funnels and two high-reaching masts which completed her silhouette.
The main battery was spread about seven twin-gunned turrets with two ahead of the bridge superstructure, two at amidships, and the remaining three collected ahead of the stern. Supplemental firepower came from 20 x 6" (152mm) BL Mk XIII guns and 10 x 3" (76mm) guns. Torpedoes could be launched by way of 3 x 21" (533mm) tubes carried.
Armor protection ranged from 229mm thickness at the belt to 64mm maximum on the deck. Her barbettes were protected up to 229mm and her turrets up to 305mm. The conning tower carried 305mm protection and the bulkheads were up to 152mm thick. Her overall displacement was 28,300 tons under standard load and 31,360 tons under full load. Dimensions included a length of 671.5 feet with a width of 89 feet and a draught of 29.9 feet.
HMS Agincourt joined others in forming the 4th Battle Squadron of the Grand Fleet at the outbreak of war. Her early months were spent on patrol and she fired her guns in anger on several occasions throughout the war including as a participant in the Battle of Jutland - the largest naval confrontation of the war - which led to a tactically-inconclusive victory but allowed Britain to retain control over North Sea functions from Germany. The battle took place from May 31st, to June 1st, 1916.
During 1917, her profile was redrawn some when her mainmast tripod was modified to a pole design. HMS Agincourt managed to survive all of the war which ended with an Armistice in November 1918 and lived only a short post-war existence when the British attempted to resell the proven veteran back to the Brazilian government which declined the offer. She was placed in reserve status during 1919 and officially decommissioned in April of 1921. In accordance to the newly-drafted Washington Naval Treaty, HMS Agincourt was scrapped in 1924.