The two ships of this class are essentially improved versions of the preceding HMS Neptune, with a stronger armour belt, improved internal subdivision and the elimination of the main mast, which increased stability and sea-going capability. To conserve weight, some compromises had to be made in terms of internal protection. They are the last class of capital ships to be fitted with a 12" main battery, but the first to bear the greater 21" torpedoes. Both ships were commissioned in 1911.