Monitor (warship)

A monitor was a special form of warship, little more than a self-propelled floating artillery platform that could move close inshore and give its support to military operations on land. In the twentieth century it was developed into a range of sizes adapted for use in different waters, until it was superseded by aerospace technology.

The USS *Monitor*, the original Monitor-class ship

Origins

Ship-rigged bomb vessels (left foreground) firing over the British line of battle into the Danish line (middle distance) before Copenhagen (right background). 1801

The principle of supporting a landing with ship-mounted artillery had been prepared for in the armament of the Spanish Armada of 1588, for example. The principle of supporting a land army was employed in the Battle of the Dunes in 1658. The bomb ketch was well established by the end of the seventeenth century and continued into the early nineteenth century. During the Crimean War, the French and British built "floating batteries" - screw-driven heavily armoured ships built for the sole purpose of bombardment of shore positions. The Crimean war also saw an early example of a rotating gun mount (an experiment by Captain Cowper Coles RN mounting a 32 pounder gun on a raft).

Nineteenth Century

In Latin, a monitor is someone who admonishes--that is, reminds another of his duties--which is how USS Monitor was given its name. She was designed by John Ericsson for emergency service in the Federal navy during the American Civil War. She was designed to serve in shallow water and to present as small a target as possible, the water around acting as protection. The Battle of Hampton Roads, between the Monitor and CSS Virginia, (the wreck of the frigate, USS Merrimack, converted into an ironclad floating battery) was a battle between two vessels and not typical of the action for which later monitors would be designed.

Three months after the Battle of Hampton Roads, John Ericsson took his design to his native Sweden, and in 1865 the first Swedish monitor was being built at Motala Warf in Norrköping; taking the engineers name. She was followed by 14 more monitors. One of them, Kanonbåten Sölve, served until 1922 and is today preserved at the marine museum in Gothenburg. These and others built by several navies in the 1860s and 1870s were used for coastal defence and took the name monitor as a type of ship. Those that were directly modelled on the Monitor were low-freeboard, mastless, steam-powered vessels with one or two rotating armoured turrets. The low freeboard meant that these ships were unsuitable for ocean-going duties and were always at risk of water entering the ship and causing flooding and possible loss, but it reduced the amount of armour required for protection, and in heavy weather the sea would wash over the deck rather than heeling the ship over.

Attempts were made to design monitors with sail rigs, to overcome the reliance on the steam engine, which besides its technical problems was still met with antipathy in some navies. The provision of masts interfered with the turrets' ability to operate in a 360 degree arc of fire and the weight of mast and sail aloft made the the ships less stable. One ship, HMS Captain, which combined turret and sails with a low freeboard was lost in heavy weather.

A late example of a vessel fairly directly modelled on the Monitor was the Huáscar, designed by Cowper P. Coles, the advocate and developer of turret ships for the Royal Navy. She was launched in 1865 at Birkenhead and attained fame serving the Peruvian Navy during the War of the Pacific under the command of Rear Admiral Miguel Grau. She successfully raided enemy sea lanes for several months and delayed an invasion of Chilean territory until captured by the Chilean Navy at the Battle of Angamos in 1879. Over the years, both Chile and Peru have come to venerate the ship and the officers from both sides that died on her deck, either commanding her or boarding her, as national heroes. Huáscar is currently commissioned in the Chilean Navy, has been restored to a near-original condition and, as a museum ship, is open to visitors at its berth in Talcahuano.

A more seaworthy variation was called the breastwork monitor, this raised the turrets and superstructure on a platform above the hull. These were still not particularly successful as sea-going ships, because of the short sailing range due by the low efficiency and poor reliability of the steam engines they used. The first of these ships was the HMVS Cerberus, built between 1868 and 1870. She still exists (in rather poor condition) near Melbourne, Australia.

Gunboats

The monitor, by proving the efficacy of turrets over fixed guns, played a part in development of the dreadnought battleship from the ironclad. As a shallow draft vessel it also led to the gunboat which served to intimidate potential opponents in imperial territories.

These were two specialized forms, for use on rivers and coasts respectively. There was also a class of river monitors — the strongest dedicated river warships. They were used by several imperial navies; for example, that of Japan.

Twentieth century

First World War

In the early twentieth century support of land forces ashore was given by a more developed form of the monitor. They are best regarded as self-propelled gun platforms. They were broad beamed for stability (beam was about 1/3 of the overall length) which together with a lack of emphasis on speed made them extremely slow, and they were not suitable for naval combat or any sort of work on the high seas. Monitors of the Royal Navy played a part in consolidating the left wing of the Western Front during the Race to the Sea in 1914. The monitors principally in use at this time were those of the Humber class, originally built for the Brazilian Navy as river monitors [1]. These were smaller than the later coastal monitors and of particularly shallow draught, with a single main turret forward.

File:HMS Abercrombie.jpg

HMS Abercrombie (of the Abercrombie class)

To these were added monitors built during the course of the war. Their armament was typically a turret taken from a de-commissioned pre-dreadnought battleship. These monitors were built from the start with protection against torpedo attack - waterline bulges were incorporated into the Abercrombie class of 1915. [2]. As the war settled to its longer course, these heavier monitors formed patrols along with destroyers on either side of the Straits of Dover to exclude enemy surface vessels from the English Channel and keep the enemy in port. The monitors could also operate into the river mouths, the General Wolfe which mounted a single 18 inch gun was able to shell a bridge 20 miles away near Ostend. Other RN monitors served in the Mediterranean.

The dimensions of the several classes of monitor varied greatly. Those of the Abercrombie class were 320 ft (116 m) by 90 ft (27.4 m) in the beam and drew 9 ft (3 m) compared to the M29 class monitors of 1915 that were only 170 ft (52 m) long. and th Erebus class of 1916 were 405 ft (123.5 m) long - the largest monitors carried the heaviest guns.

Second World War

The Royal Navy monitors were mostly scrapped following the First World War. As such when the requirements for shore support returned in the Second World War they had to be built again. The guns as before coming from scrapped battleships. The last U.S. Navy monitor-class warship was struck from the Navy List in 1937. However, several of these ships were still in existence, and a few more were built, to play a part in the Second World War. Allied monitors saw service in the Mediterranean in support of the British Eighth Army's desert and Italian campaigns. They were part of the offshore bombardment for the Invasion of Normandy in 1944.

Post war

The Royal Navy still had HMS Abercrombie (completed 1943) and Roberts (1941) in reserve in 1953. They were typical monitors, trunk-decked vessels, some 373 feet long overall, 90 foott in the beam and with an 11 foot mean draught carrying two 15-inch guns.

Later in the century, vessels of similar design and construction were built and gave good service in the U.S. Navy's 'Brown Water' fleet in the rivers and delta of Vietnam. These would best be described as river gunboats.

Submarines

USS Monitor had had very little freeboard so as to bring the mass of the gun turret down thereby increasing stability but also making a smaller target to shoot at. This latter idea was carried further with the concept of the Royal Navy's R class of submarine gunboats. The British M class submarines were initially designed for shore bombardment, but then redefined for attacking enemy merchant vessels - believing that their 12-inch gun would be more effective at longer range than a torpedo on a moving target. In practice only one even entered service before the end of the Great War - the same vessel, HMS M1, was lost in the English Channel in 1925. It was later discovered that she had been accidentally rammed while submerged - her gun had come free of its mount completely flooding her.

Derivative uses of the name

To overcome the stability problems arising from the heavy turret mounted high in the vessel, their hulls were designed so as to reduce other top weight. After Ericsson's ships, monitors developed the trunk deck design as the upper deck had to be heavily armoured against plunging shells. Because of the weight high in the hull, its breadth was minimized. This design thus produced a broad-beamed vessel at the waterline, with a narrow upper deck. By analogy, nineteenth century railway coaches which were of the same form to accommodate ventilators and lamps above the heads of standing passengers in the centre while to the sides, passengers were seated, were called in the U.S. monitors or monitor cars. The raised part of the roof was known in the U.S. as a turret. In ship design of around 1900, a turret deck was a more austere version of the trunk deck.

References

Anon. Jane's Fighting Ships 1953-54 (1953)
Churchill, W.S. The World Crisis 1911-1918 (1938) Chapter XVI
Oxford English Dictionary