The Battleship in this article refers to the large steel warships that evolved from HMS Dreadnought, commissioned in 1905. Previous battleships carried a mix of medium 234mm/9inch and small 76mm/3inch caliber armament, along with 2x2 set of large (305mm) caliber guns. Dreadnought changed this by introducing the idea of 'all big guns'. 5x2 305mm guns meant that Dreadnought could out range and outgun all other Battleships in the oceans at that time.
From this point the only changes that occurred to basic Battleship design was due to technological advances. They became heavier and faster, as well as longer ranged (when oil replaced coal as fuel) Gun size had reached 381mm/15inches in diameter by the First World War (Queen Elizabeth Class) and few classes of Battleship would use heavier armament. Battleship armament topped out at 460cm/18.1inch with the Japanese Yamato class. It is worth noting that both ships of the Yamato class did not get a chance to fire their guns at enemy ships, both were sunk by air attack.
From 1905 Battleships increased in size from 20,000 tons with Dreadnought, to 70,000 tons with Yamato. Speeds increased from 21knots up to 33knots with the Iowa Class.
Much to the disappointment of many Admirals (both real and armchair) there was to be no decisive clash of steel fleets after Tsushima 1905 and no major Battleship fleet on Battleship fleet battle after Jutland 1916. A few Battleship engagements occurred throughout World War 2 but the Age of Steel was over.
The 1940s saw the Aircraft Carrier almost completely rendered the Battleship impotent.
Notable Battleship Battles:
Tsushima 1905. The Japanese sink the Russian Baltic fleet, near Korea.
Jutland 1916. The German High Seas fleet escapes destruction at the hands of the British Grand Fleet, the Grand Fleet loses more ships and men, but maintains control of the North Sea.