shows the low freeboard typical for early ironclad turret-ships. This ship, launched in 1875, should not be confused with her famous successor, launched in 1906, marking the end of the pre-dreadnought era.
The pre-dreadnought developed from the ironclad battleship. The first ironclads — the French Gloire and HMS Warrior — looked much like sailing frigates, with three tall masts and broadside batteries, when they were commissioned at the start of the 1860s. Only eight years later HMVS Cerberus, the first breastwork monitor, was launched. After a further three years followed HMS Devastation, a turreted ironclad which more resembled a pre-dreadnought than previous and contemporary turretless ironclads. Each ship lacked masts and carried four heavy guns in two turrets fore and aft. Devastation was the first ocean-worthy breastwork monitor, built to attack enemy coasts and harbours; because of her very low freeboard, she could not fight on the high seas as her decks would be swept by water and spray, interfering with the working of her guns. Navies worldwide continued to build masted, turretless battleships which had sufficient freeboard and were seaworthy enough to fight on the high seas.
The distinction between coast-assault battleship and cruising battleship became blurred with the Admiral class, ordered in 1880. These ships reflected developments in ironclad design, being protected by iron-and-steel compound armour rather than wrought iron. Equipped with breech-loading guns of between 12-inch and 16 ¼-inch (305 mm and 413 mm) calibre, the Admirals continued the trend of ironclad warships towards gigantic weapons. The guns were mounted in open barbettes to save weight. Some historians see these ships as a vital step towards pre-dreadnoughts; others view them as a confused and unsuccessful design.
The subsequent Royal Sovereign class of 1889 retained barbettes but were uniformly armed with 13.5-inch (343 mm) guns; they were also significantly larger (at 14,000 tons displacement) and faster (due to triple-expansion steam engines) than the Admirals. Just as importantly, the Royal Sovereigns had a higher freeboard, making them unequivocally capable of the high-seas battleship role.
The pre-dreadnought design reached maturity in 1895 with the Majestic class. These ships were built and armoured entirely of steel, and their guns were mounted in fully enclosed barbettes, inevitably referred to as turrets. They also adopted a 12-inch (305 mm) main gun, which, due to advances in casting and propellant, was lighter and more powerful than the previous guns of larger calibre. The Majestics provided the model for battleship building in the Royal Navy and many other navies for years to come.