H.M.S. Orion was one of eight armoured vessels authorised in 1909 and one of four Orion Class Battleships known as the ‘super-dreadnoughts’. She was built at Portsmouth Royal Dockyard: keel laid November 1909; launched August 1910; commissioned January 1912. She was the lead ship of her class and spent the bulk of her career assigned to the Home and Grand Fleets, usually serving as flagship. Her participation in the failed attempt to intercept the German ships that bombarded Scarborough, Hartlepool and Whitby in late 1914 was undistinguished as her commanding officer refused to open fire on the light cruiser SMS Stralsund without an order from above. At the Battle of Jutland in May 1916 she fired 51 rounds with one known hit (on the battleship SMS Markgraf). Her remaining service during the war generally consisted of routine patrols and training in the North Sea although she was present at Rosyth when the High Seas Fleet surrendered n 21st November 1918. Her fate was sealed by the 1922 Washington Treaty that limited large ship numbers among the allied nations following the War to limit another arms race. She was sold in 1922 and broken up at Upnor on the Medway in Kent in 1923.