Superfiring turrets were developed to deal with the layout problems caused by the adoption of the all-big-gun battleship, starting with HMS Dreadnought of 1906. The majority of pre-dreadnought battleships carried four main guns, in two twin-gun turrets, one fore and one aft, giving them a four-gun broadside. For the all-big-gun ship to be worthwhile it had to be able to fire at least twice this many of its main guns in a broadside.
The initial British response, as seen in the Dreadnought was to scatter other guns around the ship. On the Dreadnought a third turret was placed in the middle of the ship. This gun could fire to either side, but not fore or aft. Two more turrets were placed on either side of the forward superstructure. These could only fire port or starboard, so of its ten guns, the Dreadnought could only use eight in the broadside.
The German solution was even less efficient. Their early dreadnoughts, the Nassau class, carried six twin-gun turrets, one fore, one aft and two on each side, needed twelve guns to fire an eight gun broadside.
The solution to this problem came from the United States, and had been under development for two years before the launch of the Dreadnought. There work had begun on the design of an all-big-gun battleship well before the British began working on the Dreadnought, but a painfully slow design process meant that the ship in question, USS South Carolina, was not laid down until 1906.
The gun layout developed by Chief Constructor Washington L. Capps was the superfiring pair of turrets. In this layout two turrets were placed in line, one turret on normal deck level, with the second turret above and behind. Both turrets could fire to either side of the ship, and in theory the second turret could fire over the top of the first against targets directly ahead or behind the ship. A ship equipped with two pairs of superfiring twin turrets would only need eight guns to fire an eight gun broadside, without most of the limits on the arcs of fire of the extra turrets imposed by other solutions.
The main concern about this arrangement of turrets was that in some circumstances the upper guns would be firing directly over the top of the lower turret. There was a real danger that this would cause blast damage to the lower turret, possibly enough to prevent the upper guns from be using against targets directly in line with the lower turret.
Accordingly, in March 1907 the monitor USS Florida, which carried a twin 12in turret, was modified. One gun was removed from the turret and placed in a position where it could fire across the top of the turret, just as would happen in the South Carolina. A series of test firing began, first with animals in the turret, and then with men. The test turret survived intact, proving that the South Carolina would be able to fire both turrets at targets directly in front of or behind her.
The South Carolina was launched in 1908. The new design was soon copied by Britain and Germany, both using it on ships laid down in 1909. HMS Neptune carried a pair of superfiring turrets at the rear, although its remaining guns were less well placed. The first British battleship to carry two pairs of superfiring turrets was HMS Orion, also laid down in 1909.
In Germany the Kaiser class of battleships were the first to carry superfiring turrets, again one pair at the rear of the ship. The Konig class, laid in 1911-1912, would be the first to feature two pairs of superfiring turrets.
Central turrets continued to be used to provide extra firepower until the appearance of 15in guns on battleships, on the British Queen Elizabeth class of 1912-1916. A variety of odd combinations of 12in guns were used in the intervening years, amongst then the six-turret layout used on the American Wyoming class battleships of 1910-1912, which carried two pairs of superfiring turrets at the rear of the ship, of which on the rear pair could actually fire to the stern.
A more practical method of increasing the number of very large guns that could be carried first appeared in the Nevada class of 1912-1916. These ships carried two pairs of superfiring turrets, with two of those turrets carrying three 14in guns. In the Pennsylvania class of 1913-1916 all four turrets carried three guns.
The first British designs to feature three gun superfiring turrets were the “N 3” type battleships, designed after the war but never built. These would have carried a pair of superfiring turrets each carrying three 18in guns at the front of the ship. The first ships to actually carry this arrangement of guns were HMS Nelson and HMS Rodney, each carrying one pair of superfiring three gun 16in turrets, laid down in 1922 but not completed for five years. The George V class went one step further, and carried two four gun turrets, carried as a superfiring pair at the front of the ship. This layout was first used by the two ships of the French Dunkerque class, which carried all eight of their 13in guns in a pair of superfiring turrets at the front of the ship.
Even the gigantic Japanese Yamato class ships did not go to this extreme, carrying three three-gun turrets, with a superfiring pair forward. This was also the standard pattern for American battleships after the First World War, although the final Montana class would have carried four three-gun turrets.