Prior to the construction of the Dreadnought, battleships tended to have guns of varying calibres located wherever they would fit on the hull, but this meant that there may only have been one or two guns of the largest calibre mounted on the ship. The Dreadnought introduced the concept of the all big-gun battleship, mounting up to 12 large calibre guns.
Dreadnought rendered all previous battleships obsolete overnight, which although being a great technical improvement, did mean that the Royal Navy's huge advantage over all other navies was effectively negated and allowed the German Navy to begin construction of a modern battle fleet on level terms with the British.