Armament
Pre-dreadnoughts carried guns of several different calibres, for different roles in ship-to-ship combat. The main armament was four heavy guns, mounted in two centreline turrets fore and aft. Very few pre-dreadnoughts deviated from this arrangement. These guns were slow-firing, and initially of limited accuracy; but they were the only guns heavy enough to penetrate the thick armour which protected the engines, magazines, and main guns of enemy battleships.
The most common calibre for the main armament was 12 inches, although some ships used smaller guns because they could attain higher rates of fire; British battleships from the Majestic class onwards carried this calibre, as did French ships from the Charlemagne class (laid down in 1894). Japan, importing most of its guns from Britain, used 12-inch guns. The United States used both 12- and 13-inch (330 mm) guns for most of the 1890s until the Maine class (not to be confused with the earlier Maine of Spanish-American War notoriety), laid down in 1899, after which the 12-inch (305 mm) gun was universal. The Russians used both 12- and 10-inch (254 mm) as their main armament; the Petropavlovsk class, Retvizan, Tsesarevich, and Borodino class had 12-inch (305 mm) main batteries while the Peresviet class mounted 10-inch (254 mm) guns. The first German pre-dreadnought class used a 11-inch (279 mm) gun but decreased to a 9.4-inch (239 mm) gun for the two following classes and returned to 11-inch guns with the Braunschweig class.
While the calibre of the main battery remained quite constant, the performance of the guns improved as longer barrels were introduced. The introduction of slow-burning nitrocellulose and cordite propellant allowed the employment of a longer barrel, and therefore higher muzzle velocity—giving greater range and penetrating power for the same calibre of shell. Between the Majestic class and Dreadnought, the length of the British 12-inch gun increased from 35 calibres to 45 and muzzle velocity increased from 2417 feet per second (737 m/s) to 2725 (830 m/s).
Pre-dreadnoughts also carried a secondary battery. This consisted of smaller guns, typically 6-inch (152 mm), though any calibre from 4 to 9.2 inches (100 to 230 mm) could be used. Virtually all secondary guns were "quick firing", employing a number of innovations to increase the rate of fire. The propellant was provided in a brass cartridge, and both the breech mechanism and the mounting were suitable for rapid aiming and reloading.
The role of the secondary battery was to damage the less well-armoured parts of an enemy battleship; while unable to penetrate the main armour belt, it might score hits on lightly armoured areas like the bridge, or start fires. Equally important, the secondary armament was to be used against enemy cruisers, destroyers, and even torpedo boats. A medium-calibre gun could expect to penetrate the light armour of smaller ships, while the rate of fire of the secondary battery was important in scoring a hit against a small, manoeuvrable target. Secondary guns were mounted in a variety of ways; sometimes carried in turrets, they were just as often positioned in fixed armoured casemates in the side of the hull, or in unarmoured positions on upper decks.
Some of the pre-dreadnoughts carried an "intermediate" battery, typically of 8-inch (203 mm) to 10-inch calibre. The intermediate battery was a method of packing more heavy firepower into the same battleship, principally of use against battleships or at long ranges. The United States Navy pioneered the intermediate battery concept in the Indiana, Iowa, and Kearsarge classes, but not in the battleships laid down between 1897 and 1901. Shortly after the USN re-adopted the intermediate battery, the British, Italian, Russian, French, and Japanese navies laid down intermediate-battery ships. This later generation of intermediate-battery ships almost without exception finished building after Dreadnought, and hence were obsolete before completion.
During the ironclad age, the range of engagements increased; in the Sino-Japanese War of 1894–5 battles were fought at around 1 mile (1,600 m), while in the Battle of the Yellow Sea in 1904, the Russian and Japanese fleets had opened fire at over 8 miles (12.8 km) before settling down to ranges at 3.5 miles (5,600 m). The increase in engagement range was due in part to the longer range of torpedoes, and in part to improved gunnery and fire control. In consequence, shipbuilders tended towards heavier secondary armament, of the same calibre that the "intermediate" battery had been previously; the Royal Navy's last pre-dreadnought class, the Lord Nelson class, carried ten 9.2-inch guns as secondary armament. Ships with a uniform, heavy secondary battery are often referred to as "semi-dreadnoughts".
The pre-dreadnought's armament was completed by a tertiary battery of light, rapid-fire guns. These could be of any calibre from 3-inch (76 mm) down to machine guns. Their role was to give short-range protection against torpedo boats, or to rake the deck and superstructure of a battleship.
In addition to their gun armament, many pre-dreadnought battleships were armed with torpedoes, fired from fixed tubes located either above or below the waterline. By the pre-dreadnought era the torpedo was typically 18 inches (46 cm) in diameter and had an effective range of several thousand yards. However, it was virtually unknown for a battleship to score a hit with a torpedo.
Read more about this topic: Pre-dreadnought Battleship