Ordnance experiments in the 1870s involving testing pressures in gun bores revealed that performance could be significantly enhanced by utilizing slower-burning gunpowder and longer barrels. Slow-burning large-grain powder, known as prismatic powder, prolonged the length of time that the charge acted on the projectile and thus increased both muzzle velocity and range. The problem with this was that the projectile left the barrel before all the powder was consumed. This could be solved by longer barrels, but that made muzzle-loading next to impossible. The slower-burning powders also required a powder chamber of diameter larger than that of the bore. All these factors, and the need to protect gun crews during the loading process, prompted a renewed search for an effective breech-loading gun.
Although breechloaders had been tried at sea in the modern era, beginning in 1858 in the French Gloire and later in the British Warrior, problems led to them being discarded. In 1864 the Royal Navy reverted definitively to muzzle-loading ordnance, but other nations, especially the French, moved ahead with breechloaders.
The old problem of ineffective sealing at the breech was only slowly overcome. In 1872 a French Army captain named de Bange came up with a “plastic gas check” that helped prevent escape of gases at the breech, and in 1875 France adopted the breechloader. At the same time brass cartridge cases, already used for small arms, came into use for the smaller breech-loading guns.
An accident aboard HMS Thunderer in the Sea of Marmora in January 1879 helped prompt the Royal Navy’s return to breechloaders. Simultaneous firing was under way, with the main guns fired in salvo; during this, one of the battleship’s 12-inch muzzle-loading guns misfired. This was not detected from the force of the discharge of the one gun, and both guns were run back in hydraulically to be reloaded. When they were again fired the double-charged gun blew up, killing 11 men and injuring 35 others. This could not have happened with a breech-loading gun, and in May the Admiralty set up a committee to investigate the merits of breech-loading versus muzzle-loading guns. In August 1879 after a committee of officers examined new breechloaders built by Armstrong in Britain and Krupp in Germany, the Royal Navy decided to utilize the breechloader in three battleships entering service in 1881-1882.
Another change in the period was to guns of steel, which accompanied enormous increases in gun size. Krupp in Germany began producing cast steel rifled guns in 1860. The change to steel guns was made possible by the production of higher-quality steel. At the same time that the Royal Navy went to the breechloader it adopted the all-steel gun, in which a steel jacket was shrunk over a steel tube and layers of steel hoops were then shrunk over this. The system of jackets and hoops over an inner steel tube was followed by one in which steel wire was spun on under tension varying with the distance from the bore. This helped eliminate barrel droop. Such “wire guns” continued in British service until the 1930s. Bore lengths of the guns increased from 35 to 45 calibers and even from 40 to 45 calibers.
The larger guns of the period required mechanized ammunition hoists and complex breech-loading gear. Their metal carriages recoiled on inclined metal slides that pivoted under the gun port. The slides were trained laterally by means of transverse truck wheels moving on racers, iron paths set into the ship’s deck.
Naval Gun Turret
Following the decision to arm ships with a few large-bore pivot-mounted guns as their principal armament, the next step was an armored turret to protect the guns and their crews, especially during the lengthy reloading process. During the Crimean War (1853-1856), Royal Navy captain Cowper Coles designed two floating batteries to engage Russian shore batteries at close range. The second of these mounted a 68-pounder protected by a hemispheric iron shield, which during action proved largely impervious to hostile fire.
In March 1859 Coles patented the idea of turrets aboard ship. He advocated guns mounted on the centerline of the vessel so as to have wide arcs of fire on either side of the ship and halving the number of guns previously required for broadsides fire. Coles’s persistence, coupled with the powerful support of Prince Albert, led the Admiralty in March 1861 to install an experimental armored turret on the floating battery Trusty. The test was a success, for 33 hits from 68-pounder and 100-pounder guns failed to disable it.
The Coles turret turned on a circumferential roller path set in the lower deck, operated by two men with a hand crank. Its upper 4.5 feet of armor came up through the main or upper deck and formed an armored glacis to protect the lower part. The crew and ammunition entered the turret from below through a hollow central cylinder.
The first British seagoing turreted ship was the Coles-inspired Prince Albert of 1864. It mounted four 9-inch muzzle-loading rifles, one each in four centerline circular turrets, turned by hand; 18 men could complete a revolution in one minute. The problem of centerline turrets in a ship of high superstructure and sail rig and very low freeboard (the latter the result of a design error) contributed to the disastrous loss at sea of the Coles-designed HMS Captain in 1870. Most of its crew drowned, Coles among them.
In the United States, John Ericsson’s single revolving turret the Monitor entered service in March 1862. The Monitor and many follow-on types all had very low freeboard. This lessened the amount of armor required to protect the ship, allowing it to be concentrated in the turret. Unlike the Captain, however, the Monitor had no high superstructure or sail rig.
Ericsson’s turret was all above the upper deck, on which it rested. Before the turret could be turned, it had to be lifted by rack and pinion from contact with the deck. A steam engine operating through gearing turned the turret around a central spindle. The Monitor was the first time that a revolving turret had actually been employed in battle, in its March 9, 1862, engagement with CSS Virginia.
Sharp disagreement continued between those who favored the revolving turret and supporters of broadside armament. Renewed interest in the ram-in consequence of the 1866 Battle of Lissa-and larger, more powerful guns helped decide this in favor of the turret. The ram meant that ships had to fire ahead as they prepared to attack an opposing vessel; heavier guns meant that ships needed fewer of them and that these should have the widest possible arc of fire. The elimination of sail rigs and improved ship designs heightened the stability of turreted warships.
Turrets continued to undergo design refinement and received new breech-loading guns as well as heavier armor, indeed the thickest aboard ship. Relatively thin top-of-turret armor on British battle cruisers, however, led to the loss of three of them to German armor-piercing shells in the Battle of Jutland (May 31-June 1, 1916). The battle cruiser turrets also lacked flash-protection doors and the means of preventing a shell burst inside the turret from reaching the magazines. The largest battleship ever built, the Japanese Yamato had 25.6 inches of steel armor protection on its turrets.
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Lambert, Andrew, ed. Steam, Steel & Shellfire: The Steam Warship, 1815-1905. Annapolis, MD: Naval Institute Press, 1992.
Padfield, Peter. Guns at Sea. New York: St. Martin’s, 1974.
Tucker, Spencer C. Handbook of 19th Century Naval Warfare. Stroud, UK: Sutton, 2000.
Hawkey, Arthur. Black Night off Finisterre: The Tragic Tale of an Early British Ironclad. Annapolis, MD: Naval Institute Press, 1999.
Hough, Richard. Fighting Ships. New York: Putnam, 1969.