Submarine warfare

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H.L. Hunley, the first submarine to sink an enemy vessel in combat. Css hunley on pier.jpg
H.L. Hunley, the first submarine to sink an enemy vessel in combat.

Submarine warfare is one of the four divisions of underwater warfare, the others being anti-submarine warfare, mine warfare and mine countermeasures.

Underwater warfare One of the three operational areas of naval warfare

Underwater warfare is one of the three operational areas of naval warfare, the others being surface warfare and aerial warfare. It refers to combat conducted underwater such as:

Anti-submarine warfare Branch of naval warfare

Anti-submarine warfare is a branch of underwater warfare that uses surface warships, aircraft, or other submarines to find, track, and deter, damage, or destroy enemy submarines.

Naval mine explosive weapon for use in seas and waterways, triggered by the targets approach

A naval mine is a self-contained explosive device placed in water to damage or destroy surface ships or submarines. Unlike depth charges, mines are deposited and left to wait until they are triggered by the approach of, or contact with, any vessel. Naval mines can be used offensively, to hamper enemy shipping movements or lock vessels into a harbour; or defensively, to protect friendly vessels and create "safe" zones.

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Submarine warfare consists primarily of diesel and nuclear submarines using torpedoes, missiles or nuclear weapons, as well as advanced sensing equipment, to attack other submarines, ships, or land targets. Submarines may also be used for reconnaissance and landing of special forces as well as deterrence. In some navies they may be used for task force screening. The effectiveness of submarine warfare partly depends on the anti-submarine warfare carried out in response.

Diesel engine Internal combustion engine with quality rotational frequency governing, internal mixture formation, lean air-fuel-ratio, diffusion flame and compression ignition

The Diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel, which is injected into the combustion chamber, is caused by the elevated temperature of the air in the cylinder due to the mechanical compression. Diesel engines work by compressing only the air. This increases the air temperature inside the cylinder to such a high degree that atomised Diesel fuel injected into the combustion chamber ignites spontaneously. With the fuel being injected into the air just before combustion, the dispersion of the fuel is uneven; this is called a heterogenous air-fuel mixture. The process of mixing air and fuel happens almost entirely during combustion, the oxygen diffuses into the flame, which means that the Diesel engine operates with a diffusion flame. The torque a Diesel engine produces is controlled by manipulating the air ratio; this means, that instead of throttling the intake air, the Diesel engine relies on altering the amount of fuel that is injected, and the air ratio is usually high.

A nuclear submarine is a submarine powered by a nuclear reactor. The performance advantages of nuclear submarines over "conventional" submarines are considerable. Nuclear propulsion, being completely independent of air, frees the submarine from the need to surface frequently, as is necessary for conventional submarines. The large amount of power generated by a nuclear reactor allows nuclear submarines to operate at high speed for long periods of time; and the long interval between refuelings grants a range virtually unlimited, making the only limits on voyage times being imposed by such factors as the need to restock food or other consumables.

Torpedo self-propelled underwater weapon

A modern torpedo is a self-propelled weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with its target or in proximity to it.

American Civil War

The age of submarine warfare began during the American Civil War. The 1860s was a time of many turning points in terms of how naval warfare was fought. Many new types of warships were being developed for use in the United States and Confederate States Navies. Submarine watercraft were among the newly created vessels. The first sinking of an enemy ship by a submarine occurred on 17 February 1864, when the Confederate submarine H. L. Hunley, a privateer sank the sloop USS Housatonic in Charleston Harbor, South Carolina. Shortly afterward, however, H. L. Hunley sank, with the loss of her entire crew of eight.

American Civil War Civil war in the United States from 1861 to 1865

The American Civil War was a war fought in the United States from 1861 to 1865, between the North and the South. The Civil War is the most studied and written about episode in U.S. history. Primarily as a result of the long-standing controversy over the enslavement of black people, war broke out in April 1861 when secessionist forces attacked Fort Sumter in South Carolina shortly after Abraham Lincoln had been inaugurated as the President of the United States. The loyalists of the Union in the North proclaimed support for the Constitution. They faced secessionists of the Confederate States in the South, who advocated for states' rights to uphold slavery.

United States Federal republic in North America

The United States of America (USA), commonly known as the United States or America, is a country composed of 50 states, a federal district, five major self-governing territories, and various possessions. At 3.8 million square miles, the United States is the world's third or fourth largest country by total area and is slightly smaller than the entire continent of Europe's 3.9 million square miles. With a population of over 327 million people, the U.S. is the third most populous country. The capital is Washington, D.C., and the largest city by population is New York City. Forty-eight states and the capital's federal district are contiguous in North America between Canada and Mexico. The State of Alaska is in the northwest corner of North America, bordered by Canada to the east and across the Bering Strait from Russia to the west. The State of Hawaii is an archipelago in the mid-Pacific Ocean. The U.S. territories are scattered about the Pacific Ocean and the Caribbean Sea, stretching across nine official time zones. The extremely diverse geography, climate, and wildlife of the United States make it one of the world's 17 megadiverse countries.

Navy Military branch of service primarily concerned with naval warfare

A navy or maritime force is the branch of a nation's armed forces principally designated for naval and amphibious warfare; namely, lake-borne, riverine, littoral, or ocean-borne combat operations and related functions. It includes anything conducted by surface ships, amphibious ships, submarines, and seaborne aviation, as well as ancillary support, communications, training, and other fields. The strategic offensive role of a navy is projection of force into areas beyond a country's shores. The strategic defensive purpose of a navy is to frustrate seaborne projection-of-force by enemies. The strategic task of the navy also may incorporate nuclear deterrence by use of submarine-launched ballistic missiles. Naval operations can be broadly divided between riverine and littoral applications, open-ocean applications, and something in between, although these distinctions are more about strategic scope than tactical or operational division.

World War I

Submarine warfare in World War I was primarily a fight between German and Austro-Hungarian U-boats and supply convoys bound for the United Kingdom, France, and Russia. British and Allied submarines conducted widespread operations in the Baltic, North, Mediterranean and Black Seas along with the Atlantic Ocean. Only a few actions occurred outside the wider European-Atlantic theatre. German submarine attacks on Allied merchant ships, especially the sinking of Lusitania, turned American public opinion against the Central Powers. The U.S. demanded it stop, and Germany did so. Admiral Henning von Holtzendorff (1853–1919), chief of the admiralty staff, argued successfully in January 1917 to resume the attacks and thus starve the British. The German high command realized the resumption of unrestricted submarine warfare meant war with the United States but calculated that American mobilization would be too slow to stop a German victory on the Western Front. [1] [2] and played a large role in the United States entering the war in April 1917.

U-boat German submarine of the First or Second World War

U-boat is an anglicised version of the German word U-Boot[ˈuːboːt](listen), a shortening of Unterseeboot, literally "underseaboat." While the German term refers to any submarine, the English one refers specifically to military submarines operated by Germany, particularly in the First and Second World Wars. Although at times they were efficient fleet weapons against enemy naval warships, they were most effectively used in an economic warfare role and enforcing a naval blockade against enemy shipping. The primary targets of the U-boat campaigns in both wars were the merchant convoys bringing supplies from Canada and other parts of the British Empire, and from the United States to the United Kingdom and to the Soviet Union and the Allied territories in the Mediterranean. German submarines also destroyed Brazilian merchant ships during World War II, causing Brazil to declare war on the Axis powers in 1944.

Allies of World War I group of countries that fought against the Central Powers in World War I

The Allies of World War I or Entente Powers is the term commonly used for the coalition that opposed the Central Powers of Germany, Austria-Hungary, the Ottoman Empire and Bulgaria during the First World War (1914–1918).

Baltic Sea A sea in Northern Europe bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands

The Baltic Sea is a marginal sea of the Atlantic Ocean, enclosed by Denmark, Estonia, Finland, Latvia, Lithuania, Sweden, northeast Germany, Poland, Russia and the North and Central European Plain.

All participants were supposed to abide by the Hague Conventions of 1899 and 1907, but this was found to be impracticable for submarines. The German government maintained the British naval blockade was illegal under international law. Initially, German submarines did attempt to comply with the prize rules, but later switched to unrestricted submarine warfare following the British introduction of Q-ships with concealed deck guns. American diplomatic pressure forced the Germans to stop this for a while, but in January 1917 Germany declared a war zone around the British Isles and sank up to a quarter of shipping entering it, until escorted convoys were introduced. [3] The sinking of HMS Pathfinder was the first combat victory of a modern submarine, [4] and the exploits of SM U-9, which sank three British cruisers in under an hour, established the submarine as an important new component of naval warfare. [5]

Hague Conventions of 1899 and 1907 Treaties helping establish international law

The Hague Conventions of 1899 and 1907 are a series of international treaties and declarations negotiated at two international peace conferences at The Hague in the Netherlands. Along with the Geneva Conventions, the Hague Conventions were among the first formal statements of the laws of war and war crimes in the body of secular international law. A third conference was planned for 1914 and later rescheduled for 1915, but it did not take place due to the start of World War I.

Blockade of Germany

The Blockade of Germany, or the Blockade of Europe, occurred from 1914 to 1919. It was a prolonged naval operation conducted by the Triple-Entente powers during and after World War I in an effort to restrict the maritime supply of goods to the Central Powers, which included Germany, Austria-Hungary and the Ottoman Empire. It is considered one of the key elements in the eventual Allied victory in the war. The German Board of Public Health in December 1918 claimed that 763,000 German civilians died from starvation and disease caused by the blockade up until the end of December 1918. An academic study done in 1928 put the death toll at 424,000.

Q-ship ship type

Q-ships, also known as Q-boats, decoy vessels, special service ships, or mystery ships, were heavily armed merchant ships with concealed weaponry, designed to lure submarines into making surface attacks. This gave Q-ships the chance to open fire and sink them.

German submarines were used to lay naval mines and to attack iron ore shipping in the Baltic. The British submarine flotilla in the Baltic operated in support of the Russians until the Treaty of Brest-Litovsk. During the war, the British invested efforts into developing a submarine that could operate in conjunction with a battleship fleet – the "Fleet Submarine". To achieve the necessary 20 knots (37 km/h) (surfaced) the K-class submarines were steam powered. In practice, the K class were a constant problem and could not operate effectively with a fleet.

Iron ore ore rich in iron or the element Fe

Iron ores are rocks and minerals from which metallic iron can be economically extracted. The ores are usually rich in iron oxides and vary in colour from dark grey, bright yellow, or deep purple to rusty red. The iron is usually found in the form of magnetite (Fe
3
O
4
, 72.4% Fe), hematite (Fe
2
O
3
, 69.9% Fe), goethite (FeO(OH), 62.9% Fe), limonite (FeO(OH)·n(H2O), 55% Fe) or siderite (FeCO3, 48.2% Fe).

British submarine flotilla in the Baltic

A British submarine flotilla operated in the Baltic Sea for three years during the First World War. The squadron of nine submarines was attached to the Russian Baltic Fleet. The main task of the flotilla was to prevent the import of iron ore from Sweden to Imperial Germany. The success of the flotilla also forced the German Navy in the Baltic to keep to their bases and denied the German High Seas Fleet a training ground. The flotilla was based in Reval (Tallinn), and for most of its career commanded by Captain Francis Cromie.

Treaty of Brest-Litovsk separate peace treaty that the Soviet government was forced to sign on March 3, 1918

The Treaty of Brest-Litovsk was a peace treaty signed on March 3, 1918 between the new Bolshevik government of Russia and the Central Powers, that ended Russia's participation in World War I. The treaty was signed at German-controlled Brest-Litovsk, after two months of negotiations. The treaty was agreed upon by the Russians to stop further invasion. According to the treaty, Soviet Russia defaulted on all of Imperial Russia's commitments to the Allies and eleven nations became independent in Eastern Europe and western Asia.

Interwar period

Between the wars, navies experimented with submarine cruisers (France, Surcouf), submarines armed with battleship caliber guns (UK, HMS M1) and submarines capable of carrying small aircraft for reconnaissance (HMS M2 and Surcouf).

Germany was denied submarines by the terms of the Treaty of Versailles, but built some anyway. This was not legitimized until the Anglo-German Naval Agreement of 1935, under which the UK accepted German parity in submarine numbers with the Royal Navy.

World War II

In World War II, submarine warfare was split into two main areas – the Atlantic and the Pacific. The Mediterranean Sea was also a very active area for submarine operations. This was particularly true for the British and French, as well as the Germans. The Italians were also involved, but achieved their greatest successes using midget submarines and human torpedoes.

Atlantic Ocean

Grand Admiral Erich Raeder with Otto Kretschmer (left), who was the most successful German U-boat commander, August 1940 Bundesarchiv Bild 101II-MW-0952-17, Frankreich, Auszeichnungen fur U-99-Besatzung.jpg
Grand Admiral Erich Raeder with Otto Kretschmer (left), who was the most successful German U-boat commander, August 1940

In the Atlantic, where German submarines again sought out and attacked Allied convoys, this part of the war was very reminiscent of the latter part of World War I. Many British submarines were active as well, particularly in the Mediterranean and off Norway, against Axis warships, submarines and merchant shipping.

Initially, Hitler ordered his submarines to abide by the prize rules, but this restriction was withdrawn in December 1939. Although mass attacks by submarine had been carried out in World War I, the "wolf pack" was mainly a tactic of World War II U-boats. The main steps in this tactic were as follows:

With the later increase in warship and aircraft escorts, U-boat losses became unacceptable. Many boats were lost, and the earlier experienced commanders with them.

Pacific Ocean

In the Pacific, the situation was reversed, with US submarines hunting Japanese shipping. By war's end, US submarines had destroyed over half of all Japanese merchant ships, [6] totaling well over five million tons of shipping. [6] British and Dutch submarines also took part in attacks on Japanese shipping, mostly in coastal waters. Japanese submarines were initially successful, destroying two US fleet aircraft carriers, a cruiser, and several other ships. However, following a doctrine that concentrated on attacking warships, rather than more-vulnerable merchantmen, the smaller Japanese fleet proved ineffectual in the long term, while suffering heavy losses to Allied anti-submarine measures. Italian submarines and one German submarine [7] operated in the Pacific Ocean, but never enough to be an important factor, inhibited by distance and difficult relations with their Japanese ally.

Other areas

Mediterranean Sea

Indian Ocean

Japanese submarines operated in the Indian Ocean, forcing the British surface fleet to withdraw to the east coast of Africa. Some German and Italian submarines operated in the Indian Ocean, but never enough to play a significant role. [7]

Post-World War II

Since the Second World War, several wars, such as the Korean War, Indo-Pakistani War of 1971 and the Falklands War, have involved limited use of submarines. Later submarine-launched land-attack missiles were employed against Iraq and Afghanistan. With these exceptions, submarine warfare ceased after 1945. Hence strategic thinking about the role of submarines has developed independently of actual experience.

The advent of the nuclear-powered submarine in the 1950s brought about a major change in strategic thinking about submarine warfare. These boats could operate faster, deeper and had much longer endurance. They could be larger and so became missile launching platforms. In response to this the attack submarine became more important, particularly in regard to its postulated role as a hunter-killer. The US also used nuclear submarines as radar pickets for a while. There have also been major advances in sensors and weapons.

During the Cold War, the United States and the Soviet Union played what was described as a 'cat-and-mouse' game of detecting and even trailing enemy submarines.

As the likelihood of unrestricted submarine warfare has diminished, thinking about conventional submarines has focused on their use against surface warship. The mere existence of a submarine may curtail surface warships' freedom to operate. To counter the threat of these submarines, hunter submarines were developed in turn. The role of the submarine has extended with the use of submarine-launched autonomous unmanned vehicles.[ citation needed ] The development of new air independent propulsion methods has meant that the diesel-electric submarine's need to surface, making it vulnerable, has been reduced. Nuclear submarines, although far larger, could generate their own air and water for an extended duration, meaning their need to surface was limited in any case.

In today's more fractured geopolitical system, many nations are building and/or upgrading their submarines.[ citation needed ] The Japan Maritime Self-Defense Force has launched new models of submarines every few years;[ citation needed ] South Korea has upgraded the already capable Type 209(Chang Bogoclass) design from Germany and sold copies to Indonesia. [8] [9] Russia has improved the old Soviet Kilo model into what strategic analysts are calling equivalent to the 1980s-era Los Angelesclass, and so on.[ citation needed ]

At the end of his naval warfare book The Price of Admiralty, military historian John Keegan postulates that eventually, almost all roles of surface warships will be taken over by submarines, as they will be the only naval units capable of evading the increasing intelligence capabilities (space satellites, airplanes etc.) that a fight between evenly matched modern states could bring to bear on them.[ citation needed ]

However, thinking about importance of the submarine has shifted to an even more strategic role, with the advent of the nuclear ballistic missile submarine carrying Submarine-launched ballistic missiles with nuclear weapons to provide second strike capability.

Modern submarine missions

A modern submarine is a multi-role platform. It can conduct both overt and covert operations. In peacetime it can act as a deterrent as well as for surveillance operations and information gathering.

In wartime a submarine can carry out a number of missions including:

See also

Related Research Articles

Cruiser Type of large warships

A cruiser is a type of warship. Modern cruisers are generally the largest ships in a fleet after aircraft carriers and amphibious assault ships, and can usually perform several roles.

<i>Kriegsmarine</i> 1935-1945 naval warfare branch of Germanys armed forces

The Kriegsmarine was the navy of Nazi Germany from 1935 to 1945. It superseded the Imperial German Navy of the German Empire (1871–1918) and the inter-war Reichsmarine (1919–1935) of the Weimar Republic. The Kriegsmarine was one of three official branches, along with the Heer (Army) and the Luftwaffe of the Wehrmacht, the German armed forces from 1933 to 1945.

Submarine Watercraft capable of independent operation underwater

A submarine is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term most commonly refers to a large, crewed vessel. It is also sometimes used historically or colloquially to refer to remotely operated vehicles and robots, as well as medium-sized or smaller vessels, such as the midget submarine and the wet sub. The noun submarine evolved as a shortened form of submarine boat; by naval tradition, submarines are usually referred to as "boats" rather than as "ships", regardless of their size.

A tonnage war is a military strategy aimed at merchant shipping. The premise is that the enemy has a finite number of ships and a finite capacity to build replacements. The concept was made famous by German Grand Admiral Karl Dönitz, who wrote:

"The shipping of the enemy powers is one great whole. It is therefore in this connection immaterial where a ship is sunk—it must still in the final analysis be replaced by a new ship".

Unrestricted submarine warfare

Unrestricted submarine warfare is a type of naval warfare in which submarines sink vessels such as freighters and tankers without warning, as opposed to attacks per prize rules. Prize rules call for submarines to surface and search merchantmen and place crews in "a place of safety" before sinking them, unless the ship showed "persistent refusal to stop ... or active resistance to visit or search". During the First World War, the British introduced Q-ships with concealed deck guns, and armed many merchantmen, leading the Germans to ignore the prize rules; in the most dramatic episode they sank Lusitania in 1915 in a few minutes because she was carrying war munitions. The U.S. demanded it stop, and Germany did so. Admiral Henning von Holtzendorff, chief of the Admiralty staff, argued successfully in early 1917 to resume the attacks and thus starve the British. The German high command realized the resumption of unrestricted submarine warfare meant war with the United States but calculated that American mobilization would be too slow to stop a German victory on the Western Front.

Fleet submarine submarine with the speed, range, and endurance to operate as part of a navys battle fleet

A fleet submarine is a submarine with the speed, range, and endurance to operate as part of a navy's Battle Fleet. Examples of fleet submarines are the British K class and the American Gato class. Within the modern Royal Navy, the term is used for the British nuclear powered attack submarines. In the United States Navy, the term came to be used primarily for the long-range submarines that served in World War II.

Commerce raiding

Commerce raiding is a form of naval warfare used to destroy or disrupt logistics of the enemy on the open sea by attacking its merchant shipping, rather than engaging its combatants or enforcing a blockade against them. It is also known, in French, as guerre de course and, in German, Handelskrieg, from the nations most heavily committed to it historically as a strategy.

Soviet Navy naval arm of the Soviet Armed Forces

The Soviet Navy was the naval arm of the Soviet Armed Forces. Often referred to as the Red Fleet, the Soviet Navy was a large part of the Soviet Union's strategic plan in the event of a conflict with opposing super power, the United States, the North Atlantic Treaty Organization (NATO), or another conflict related to the Warsaw Pact of Eastern Europe. The influence of the Soviet Navy played a large role in the Cold War (1945-1991), as the majority of conflicts centered on naval forces.

The names of commissioned ships of the United States Navy all start with USS, for "United States Ship". Non-commissioned, primarily civilian-manned vessels of the U.S. Navy under the Military Sealift Command have names that begin with USNS, standing for "United States Naval Ship". A letter-based hull classification symbol is used to designate a vessel's type. The names of ships are selected by the Secretary of the Navy. The names are those of states, cities, towns, important persons, important locations, famous battles, fish, and ideals. Usually, different types of ships have names originated from different types of sources.

There are three major types of submarines in the United States Navy: ballistic missile submarines, attack submarines, and cruise missile submarines. All submarines in the U.S. Navy are nuclear-powered. Ballistic missile submarines have a single strategic mission of carrying nuclear submarine-launched ballistic missiles. Attack submarines have several tactical missions, including sinking ships and subs, launching cruise missiles, and gathering intelligence.

Axis naval activity in Australian waters

Although Australia was remote from the main battlefronts, there was considerable Axis naval activity in Australian waters during the Second World War. A total of 54 German and Japanese warships and submarines entered Australian waters between 1940 and 1945 and attacked ships, ports and other targets. Among the best-known attacks are the sinking of HMAS Sydney by a German raider in November 1941, the bombing of Darwin by Japanese naval aircraft in February 1942, and the Japanese midget submarine attack on Sydney Harbour in May 1942. In addition, many Allied merchant ships were damaged or sunk off the Australian coast by submarines and mines. Japanese submarines also shelled several Australian ports and submarine-based aircraft flew over several Australian capital cities.

Naval warfare in the Mediterranean during World War I conflict

There was sporadic naval warfare in the Mediterranean during World War I between the Central Powers' navies of Austria-Hungary, Germany and the Ottoman Empire and the Allied navies of Italy, France, Greece, Japan, America and the British Empire.

Allied submarines in the Pacific War

Allied submarines were used extensively during the Pacific War and were a key contributor to the defeat of the Empire of Japan.

Mediterranean U-boat Campaign (World War I) fought by Austria-Hungary and German Empire against the Allies during World War I

The Mediterranean U-boat Campaign in the Mediterranean Sea was fought by Austria-Hungary and German Empire against the Allies during World War I. It was characterised by the ability of the Central Powers to raid with near impunity during the first years of the war, causing substantial shipping losses, until the introduction of the convoy system allowed the Allies to drastically cut their losses from 1917 on.

United States Navy Naval warfare branch of the United States Armed Forces

The United States Navy (USN) is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. It is the largest and most capable navy in the world and it has been estimated that in terms of tonnage of its active battle fleet alone, it is larger than the next 13 navies combined, which includes 11 U.S. allies or partner nations. with the highest combined battle fleet tonnage and the world's largest aircraft carrier fleet, with eleven in service, and two new carriers under construction. With 319,421 personnel on active duty and 99,616 in the Ready Reserve, the Navy is the third largest of the service branches. It has 282 deployable combat vessels and more than 3,700 operational aircraft as of March 2018, making it the second largest and second most powerful air force in the world.

U-boat Campaign (World War I) World War I naval campaign fought by German U-boats against the trade routes of the Allies

The U-boat Campaign from 1914 to 1918 was the World War I naval campaign fought by German U-boats against the trade routes of the Allies. It took place largely in the seas around the British Isles and in the Mediterranean. The German Empire relied on imports for food and domestic food production and the United Kingdom relied heavily on imports to feed its population, and both required raw materials to supply their war industry; the powers aimed, therefore, to blockade one another. The British had the Royal Navy which was superior in numbers and could operate on most of the world's oceans because of the British Empire, whereas the Imperial German Navy surface fleet was mainly restricted to the German Bight, and used commerce raiders and unrestricted submarine warfare to operate elsewhere.

Atlantic U-boat campaign of World War I

The Atlantic U-boat campaign of World War I was the prolonged naval conflict between German submarines and the Allied navies in Atlantic waters—the seas around the British Isles, the North Sea and the coast of France.

Convoys in World War I

The convoy—a group of merchantmen or troopships traveling together with a naval escort—was revived during World War I (1914–18), after having been discarded at the start of the Age of Steam. Although convoys were used by the Royal Navy in 1914 to escort troopships from the Dominions, and in 1915 by both it and the French Navy to cover their own troop movements for overseas service, they were not systematically employed by any belligerent navy until 1916. The Royal Navy was the major user and developer of the modern convoy system, and regular transoceanic convoying began in June 1917. They made heavy use of aircraft for escorts, especially in coastal waters, an obvious departure from the convoy practices of the Age of Sail.

References

  1. Dirk Steffen, "The Holtzendorff Memorandum of 22 December 1916 and Germany's Declaration of Unrestricted U-boat Warfare." Journal of Military History 68.1 (2004): 215–224. excerpt
  2. See The Holtzendorff Memo (English translation) with notes
  3. Tucker, Spencer; Roberts, Priscilla Mary (9 January 2014) [2005], Daniel Ramos, ed., World War I: Encyclopedia (Digitized by Google Books online), United States: ABC-CLIO, p. 312, ISBN   9781851094202
  4. Story of the U-21, National Underwater and Marine Agency, archived from the original on 27 December 2008, retrieved 2 November 2008
  5. Helgason, Guðmundur. "WWI U-boats: U 9". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 2008-11-02.
  6. 1 2 Blair, Clay, Jr. Silent Victory (New York, 1976), p. 878.
  7. 1 2 Klemen, L (1999–2000). "The U-Boat War in the Indian Ocean". Forgotten Campaign: The Dutch East Indies Campaign 1941–1942. Archived from the original on 21 March 2011.
  8. http://nationalinterest.org/blog/the-buzz/forget-north-koreas-subs-south-korea-can-build-some-amazing-21800
  9. http://www.thejakartapost.com/news/2017/08/28/brand-new-south-korean-made-submarine-joins-indonesian-navy.html
  10. BGM-109 Tomahawk - Smart Weapons

Sources

Further reading