Orion class battleships are designed in 1909 as improved design of the Colossus-class built together with them. They are also the first ships to be equipped with 34.4cm guns, which started the super dreadnoughts (equipped with guns larger than 12 inch).
Because of the size, unlike broadside placement of Colossus' guns, Orion's are all placed along the centreline. This enabled them to concentrate the firepower from all 10 guns to one side. Orion is the first ship after the dreadnought era to have all turrets placed on the centreline.
From Portsmouth, Orion is placed into the Grand Fleet during World War 1 under Admiral Leveson of the second battle squadron in the Battle of Jutland. She is removed from the list in December 1922 and scrapped in 1923.