Merchant submarine
A merchant submarine is a type of submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

 intended for trade
Trade is the transfer of ownership of goods and services from one person or entity to another. Trade is sometimes loosely called commerce or financial transaction or barter. A network that allows trade is called a market. The original form of trade was barter, the direct exchange of goods and...

, and being without armaments, it is not considered a warship like most other types of submarines. The intended use would be blockade running
Blockade runner
A blockade runner is usually a lighter weight ship used for evading a naval blockade of a port or strait, as opposed to confronting the blockaders to break the blockade. Very often blockade running is done in order to transport cargo, for example to bring food or arms to a blockaded city...

, or to dive under arctic ice
Sea ice
Sea ice is largely formed from seawater that freezes. Because the oceans consist of saltwater, this occurs below the freezing point of pure water, at about -1.8 °C ....


Strictly speaking, only two submarines have so far been purpose-built for non-military merchant shipping use, though standard or partly converted military submarines have been used to transport smaller amounts of important cargo, especially during wartime, and large-scale proposals for modern merchant submarines have been produced by manufacturers.


Only two merchant submarines have historically been built, both in Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 during World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

. They were constructed to slip through the naval blockade of the Entente Powers
Allies of World War I
The Entente Powers were the countries at war with the Central Powers during World War I. The members of the Triple Entente were the United Kingdom, France, and the Russian Empire; Italy entered the war on their side in 1915...

, mainly enforced by the efforts of Great Britain's Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

. The British blockade had led to great difficulties for German companies in acquiring those raw materials which were not found in quantity within the German sphere of influence
Sphere of influence
In the field of international relations, a sphere of influence is a spatial region or conceptual division over which a state or organization has significant cultural, economic, military or political influence....

, and thus was hindering the German war efforts substantially.

The submarines were built in 1916 by a private shipping company created for the enterprise, the Deutsche Ozean-Reederei, a subsidiary company of the North German Lloyd
Hapag-Lloyd is a German transportation company comprising a cargo container shipping line, Hapag-Lloyd AG, which in turn owns other subsidiaries such as Hapag-Lloyd Ships and a cruise line, Hapag-Lloyd Cruises which is now integrated into TUI AG, Hanover...

 shipping company (now Hapag-Lloyd) and the Deutsche Bank
Deutsche Bank
Deutsche Bank AG is a global financial service company with its headquarters in Frankfurt, Germany. It employs more than 100,000 people in over 70 countries, and has a large presence in Europe, the Americas, Asia Pacific and the emerging markets...

. They were intended to travel the route from Germany to the neutral U.S.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, bringing back the required raw materials. As the U.S. would not profit enough from receiving German currency, the ships were to carry trade goods both ways.

Britain soon protested with the U.S. against the use of submarines as merchant ships, arguing that they could not be stopped and inspected for munitions in the same manner as other vessels. The U.S., under diplomatic
Diplomacy is the art and practice of conducting negotiations between representatives of groups or states...

 pressure for supposedly showing favoritism while having declared itself neutral
Neutral country
A neutral power in a particular war is a sovereign state which declares itself to be neutral towards the belligerents. A non-belligerent state does not need to be neutral. The rights and duties of a neutral power are defined in Sections 5 and 13 of the Hague Convention of 1907...

, rejected the argument. Even submarines, as long as they were unarmed, were to be regarded as merchant vessels and accordingly would be permitted to trade.


The Deutschland had a carrying capacity of 700 tons (much of it outside the pressure hull), and could travel at 15 kn (18.3 mph; 29.4 km/h) on the surface and 7 kn (8.5 mph; 13.7 km/h) while submerged. It had a crew of 29 men and was commanded by Paul König
Paul König
Paul König was a sailor and business executive. He is most known for two visits he made to the United States in 1916 as captain of a merchant submarine.-Biography:König was a captain in the German merchant navy...

, a former surface merchantman captain
Captain (nautical)
A sea captain is a licensed mariner in ultimate command of the vessel. The captain is responsible for its safe and efficient operation, including cargo operations, navigation, crew management and ensuring that the vessel complies with local and international laws, as well as company and flag...


On its first journey to the US, departing on the 23 June 1916, Deutschland carried 163 tons of highly sought-after chemical dye
A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber....

s, as well as medical drug
A pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...

s and mail. Passing undetected through the English Channel
English Channel
The English Channel , often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates southern England from northern France, and joins the North Sea to the Atlantic. It is about long and varies in width from at its widest to in the Strait of Dover...

 she arrived in Baltimore
Baltimore is the largest independent city in the United States and the largest city and cultural center of the US state of Maryland. The city is located in central Maryland along the tidal portion of the Patapsco River, an arm of the Chesapeake Bay. Baltimore is sometimes referred to as Baltimore...

 on the 8 July 1916 and soon reembarked with 348 tons of rubber
Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...

, 341 tons of nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...

 and 93 tons of tin
Tin is a chemical element with the symbol Sn and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4...

, arriving back in Bremerhaven
Bremerhaven is a city at the seaport of the free city-state of Bremen, a state of the Federal Republic of Germany. It forms an enclave in the state of Lower Saxony and is located at the mouth of the River Weser on its eastern bank, opposite the town of Nordenham...

 on 25 August 1916. She had traveled 8450 nmi (9,724 mi; 15,649 km), though only 190 nmi (219 mi; 352 km) of these submerged.

The profit from the journey was 17.5 million Reichsmark, more than four times the building cost, mainly because of the high prices of the patented, highly concentrated dyes, which would have cost ($ per pound in today's dollars). In return, the raw materials brought back covered the specific needs of the German war industry for several months.

A second journey in October-December of the same year was also very successful, again trading chemicals, medicines and gems for rubber, nickel, alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...

s and tin. However, the Deutschland was lightly damaged during a collision with a tug
Tuğ is a village in the Khojavend Rayon of Azerbaijan....

 in New London
New London, Connecticut
New London is a seaport city and a port of entry on the northeast coast of the United States.It is located at the mouth of the Thames River in New London County, southeastern Connecticut....

. Following his return, captain Paul König wrote a book (or possibly had it ghost-written) about the journeys of the Deutschland. The book was heavily publicized, as it was intended to sway public opinion
Propaganda is a form of communication that is aimed at influencing the attitude of a community toward some cause or position so as to benefit oneself or one's group....

 in both Germany and the U.S.

A third journey, planned for January 1917, was however aborted after the U.S. entered the war against Germany. The declaration of war had been partly because of U.S. anger over the actions of German submarines sinking shipping bound for Great Britain, sometimes just outside of American territorial waters (See SM U-53
SM U-53
SM U-53 was a German Type Mittel U U-boat of the Kaiserliche Marine during the First World War, one of the six forming the sub type 51.-Construction and commissioning:U-53 was ordered from Germaniawerft, Kiel in 1914 and launched in 1916...

). The Deutschland was taken over by the German Imperial Navy
Kaiserliche Marine
The Imperial German Navy was the German Navy created at the time of the formation of the German Empire. It existed between 1871 and 1919, growing out of the small Prussian Navy and Norddeutsche Bundesmarine, which primarily had the mission of coastal defense. Kaiser Wilhelm II greatly expanded...

 and converted into the submarine cruiser (U-kreuzer) U-155 (a type of submarine with added artillery to fight when surfaced). It was successful in three war cruises, sinking 43 ships. After the war it was taken to England as a war trophy in December 1918. Scrapped in 1921, the boat's history ended on a tragic note, with 5 workers dying due to an explosion ripping apart the sub during dismantling.


A second merchant submarine, the sister ship of Deutschland, was launched on its first journey in August 1916 under Karl Schwartzkopf, but never arrived in the US. Its fate was never decisively uncovered, though she may have collided with the British armed merchant cruiser HMS Mantua south of Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...

, as was theorized after the war. There are also presumptions that she might have hit a mine
Naval mine
A naval mine is a self-contained explosive device placed in water to 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, an enemy vessel...

 off the Orkney Islands
Orkney Islands
Orkney also known as the Orkney Islands , is an archipelago in northern Scotland, situated north of the coast of Caithness...


Other boats

Six further merchant submarines were in the process of being built by the Deutsche Ozean-Reederei when the US entered the war in early 1917. The construction of the merchant submarines was subsequently halted or changed into submarine cruisers, similar to the fate of Deutschland.

In World War II, Germany used milk cow
German Type XIV submarine
The Type XIV U-boat was a modification of the Type IXD, designed to resupply other U-boats. They were nicknamed "Milchkuh/Milchkühe " . They had no torpedo tubes or deck guns, only anti-aircraft guns. Due to its large size, the Type XIV could resupply other boats with 400 tons of fuel, four...

submarines to refuel its hunter u-boat
U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...

s in the Atlantic. As these boats were part of Kriegsmarine
The Kriegsmarine was the name of the German Navy during the Nazi regime . It superseded the Kaiserliche Marine of World War I and the post-war Reichsmarine. The Kriegsmarine was one of three official branches of the Wehrmacht, the unified armed forces of Nazi Germany.The Kriegsmarine grew rapidly...

 (Nazi Germany's navy), did carry light armaments (anti-aircraft guns), and never engaged in trade as such, they do not qualify as merchant submarines. However, they shared the large amounts of cargo space compared to normal submarines of their day.

Germany forcibly acquired five Italian 'merchant submarines' (again having defensive armament and thus not legally merchant ships, though having many of the appropriate characteristics) from a relatively extensive Italian program after the Italian armistice in September 1943. For details see 'Italy' below.

World War II

A 12-boat 'R' class
Italian R class submarine
The R-class or Romolo-class were a group of submarines built for the Italian Royal Navy during World War II. These submarines were designed as blockade running transport submarines for transporting high-value cargo from Europe to Japan and from Japan to Europe...

 of 2100-ton submarines had been designed in Italy to carry approximately 600 tons of cargo with a surface speed of 13 kn (15.8 mph; 25.5 km/h) and submerged speed of 6 kn (7.3 mph; 11.8 km/h). A 63-man crew would operate a defensive armament of three 20 mm guns. Romolo and Remo were laid down in July 1942 at the Tosi Yard in Taranto
Taranto is a coastal city in Apulia, Southern Italy. It is the capital of the Province of Taranto and is an important commercial port as well as the main Italian naval base....

 with launch scheduled for March 1943. Ten large submarines built for combat service were also scheduled for conversion to merchant service after their designs had been found unsuitable for use against allied convoys. These were the 880-ton Archimede, the 940-ton Barbarigo, the 951-ton Comandante Cappellini, the 1030-ton Alpino Bagnolini and Reginaldo Giuliani, the 1036-ton Leonardo da Vinci and Luigi Torelli, the 1331-ton Enrico Tazzoli and Giuseppe Finzi, and the 1504-ton Ammaraglio Cagni.

Conversions were to be accomplished at Bordeaux
Bordeaux is a port city on the Garonne River in the Gironde department in southwestern France.The Bordeaux-Arcachon-Libourne metropolitan area, has a population of 1,010,000 and constitutes the sixth-largest urban area in France. It is the capital of the Aquitaine region, as well as the prefecture...

, with armament limited to defensive machine-guns, while the conversion cargo capacity of 160 tons also reduced reserve buoyancy from 20–25% to 3.5–6%. Several French submarines captured at Bizerta were also scheduled for conversion, being the 974-ton Phoque, Requin, Espadon, and Dauphin.

The ships were used on an eastbound route from Bordeaux to Singapore
Singapore , officially the Republic of Singapore, is a Southeast Asian city-state off the southern tip of the Malay Peninsula, north of the equator. An island country made up of 63 islands, it is separated from Malaysia by the Straits of Johor to its north and from Indonesia's Riau Islands by the...

 (then in Japanese, thus Axis
Axis Powers
The Axis powers , also known as the Axis alliance, Axis nations, Axis countries, or just the Axis, was an alignment of great powers during the mid-20th century that fought World War II against the Allies. It began in 1936 with treaties of friendship between Germany and Italy and between Germany and...

, hands) with cargoes of mercury, steel and aluminum bars, welding steel, bomb prototypes, 20 mm guns, blueprints for tanks and bombsights, and up to a dozen passengers. Return trip loadings were 110 to 155 tons of rubber, 44 to 70 tons of zinc, 5 tons of tungsten, 2 tons of quinine, 2 tons of opium, bamboo, rattan and passengers. Comandante Cappellini, Reginaldo Giuliani, and Enrico Tazzoli departed Bordeaux in May, 1943. The first two completed their voyages in July and August, but Enrico Tazzoli was destroyed by allied bombers in the Bay of Biscay
Bay of Biscay
The Bay of Biscay is a gulf of the northeast Atlantic Ocean located south of the Celtic Sea. It lies along the western coast of France from Brest south to the Spanish border, and the northern coast of Spain west to Cape Ortegal, and is named in English after the province of Biscay, in the Spanish...

. Barbarigo was similarly destroyed during a June departure, but Luigi Torrelli reached Singapore in August.

Following the Italian armistice in September, Giuseppe Finzi and Alpino Bagnolini were seized by Germany while undergoing conversion at Bordeaux, and designated UIT-21 and UIT-22, respectively. Reginaldo Giuliani, Commandante Cappellini, and Luigi Torelli were seized by the Japanese in the East Indies
East Indies
East Indies is a term used by Europeans from the 16th century onwards to identify what is now known as Indian subcontinent or South Asia, Southeastern Asia, and the islands of Oceania, including the Malay Archipelago and the Philippines...

, given to Germany, and designated UIT-23, UIT-24 and UIT-25, respectively. UIT-22 departed Bordeaux for Sumatra
Sumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...

 in January 1944 and was destroyed by RAF 262 squadron Catalina bombers off South Africa in March. UIT-23 was sunk by the British submarine HMS Tally-Ho in February. UIT-24 departed Sumatra for Bordeaux in February, but returned to Sumatra in March after its refueling ship was sunk.

Of the other ships, Ammiraglio Cagni surrendered at South Africa, Archimede and Leonardo da Vinci were sunk before conversion to merchant service while Romolo, Remo and the French Phoque were sunk prior to loading. The remaining "R" class submarines were not completed and conversion work ceased on the remaining three French submarines.


The Soviet Union had plans to construct cargo submarines both during World War II and in the Cold War, but these plans were never carried out. These would not strictly count as merchant submarines, as they would have been at least lightly armed and used mainly for directly war-related duties, such as supplying troops or delivering military forces to their targets. However, in the post-Cold War period, Soviet designers also proposed purely peaceful applications.

World War II

In World War II, the Soviet Union used submarines (as well as other ships) to supply the besieged Crimea
Crimea , or the Autonomous Republic of Crimea , is a sub-national unit, an autonomous republic, of Ukraine. It is located on the northern coast of the Black Sea, occupying a peninsula of the same name...

n port of Sevastopol
Sevastopol is a city on rights of administrative division of Ukraine, located on the Black Sea coast of the Crimea peninsula. It has a population of 342,451 . Sevastopol is the second largest port in Ukraine, after the Port of Odessa....

. The largest could transfer up to 95 tons of cargo, loading even the torpedo tubes with supplies. Around 4,000 tons were delivered by about 80 runs of 27 submarines, though Sevastopol still eventually fell.

Based on this experience, the Soviet Navy's high command initiated a transport submarine program. A first project (Project 605) envisaged a sub that would be basically a towed barge, connected to a standard sub. This idea was discarded due to difficulties with the towing. Later, a small cargo submarine design (Project 607) with a capacity of 250 to 300 tons of solid cargo and two folding cargo cranes was proposed. No weapons beyond two deck guns were envisaged, and the design borrowed many existing parts from the earlier VI and VI-bis submarine series
Soviet M class submarine
The M-class submarines, also Malyutka-class , were a class of small, single-, or 1½-hulled submarines built in the Soviet Union and used during World War II. The submarines were built in sections so they could easily be transported by rail...

 to simplify construction. However, by 1943 the strategic situation had changed, and the plans were not executed.

Cold War

The Soviet Union envisaged and almost realized various concepts for large cargo submarines during the 1950s and 1960s, though these would not have been counted as merchant ships, being envisaged as navy landing ships to transport troops. They would have been amongst the largest submarines of their day, had they been built.

Post Cold War

In the 1990s, the Malachite design bureau proposed plans for submarines capable of transporting petroleum
Petroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. Petroleum is recovered mostly through oil drilling...

 or freight containers
Containerization is a system of freight transport based on a range of steel intermodal containers...

 in or through Arctic regions. It was envisaged that these ships would dive under the polar ice cap
Polar ice cap
A polar ice cap is a high latitude region of a planet or natural satellite that is covered in ice. There are no requirements with respect to size or composition for a body of ice to be termed a polar ice cap, nor any geological requirement for it to be over land; only that it must be a body of...

 to travel directly between European and Asian ports, and possibly northern Canada, with the designers noting that:
The tanker and container variants would follow the same design as standard military nuclear submarines, with the tanker variant carrying almost 30,000 tons of petroleum, to be loaded and discharged from surface or underwater terminals. The container carrier was to transport 912 standard (20-foot) freight containers, loaded within 30 hours through hatches, assisted by internal conveyance systems. However, these plans came to nothing in the hard financial straits following the Soviet Union’s dissolution later in the 1990s.

A similar design has been proposed by the Rubin Design Bureau
Rubin Design Bureau
Rubin Central Design Bureau for Marine Engineering in Saint Petersburg is one of the main Russian centers of submarine design, having designed more than two-thirds of all nuclear submarines in the Russian Navy...

 with the 'Submarine Cargo Vessel
Submarine Cargo Vessel
The Submarine Cargo Vessel is a proposed idea from the Russian Rubin Design Bureau. The idea is to utilise decommissioned SSBNs from the Russian Navy to carry cargo under the Arctic Ocean...

', a civilian redesign of the famous Typhoon class submarine
Typhoon class submarine
The Project 941 or Akula, Russian "Акула" class submarine is a type of nuclear-powered ballistic missile submarine deployed by the Soviet Navy in the 1980s...

 of the Cold War.


Similar to the post-Cold War ideas of the Soviet Union, there have been some concept plans to use atomic-powered submarine oil tanker
Oil tanker
An oil tanker, also known as a petroleum tanker, is a merchant ship designed for the bulk transport of oil. There are two basic types of oil tankers: the crude tanker and the product tanker. Crude tankers move large quantities of unrefined crude oil from its point of extraction to refineries...

s to exploit Arctic oilfields in Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

 and Siberia
Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...

. General Dynamics
General Dynamics
General Dynamics Corporation is a U.S. defense conglomerate formed by mergers and divestitures, and as of 2008 it is the fifth largest defense contractor in the world. Its headquarters are in West Falls Church , unincorporated Fairfax County, Virginia, in the Falls Church area.The company has...

 had apparently approached German shipbuilders during the early 1980s about the possible construction of either a US$725 million nuclear-powered or a US$700 million methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

-powered version of a liquefied natural gas
Liquefied natural gas
Liquefied natural gas or LNG is natural gas that has been converted temporarily to liquid form for ease of storage or transport....

 (LNG) submarine tanker to carry LNG from the Arctic to North America and Europe.

Other uses

Another (albeit black market) type of 'trade' usage is the known use of narco submarine
Narco submarine
A narco-submarine is a type of custom-made ocean-going self-propelled submersible vessel built by drug traffickers to smuggle drugs. They are especially known to be used by Colombian drug cartel members to export cocaine from Colombia to Mexico, which is often then transported overland to the...

s or 'drug subs' by drug smugglers. In one case, a Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...

n drug cartel was even interrupted before finishing the construction of a professional-grade, 30 m long, 200 tons carrying-capacity submarine apparently intended for the cocaine
Cocaine is a crystalline tropane alkaloid that is obtained from the leaves of the coca plant. The name comes from "coca" in addition to the alkaloid suffix -ine, forming cocaine. It is a stimulant of the central nervous system, an appetite suppressant, and a topical anesthetic...

 trade with the U.S. Ironically, at the time of the police raid, the submarine was being constructed in segmented parts in a warehouse high in the Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...

 near Bogotá
Bogotá, Distrito Capital , from 1991 to 2000 called Santa Fé de Bogotá, is the capital, and largest city, of Colombia. It is also designated by the national constitution as the capital of the department of Cundinamarca, even though the city of Bogotá now comprises an independent Capital district...

. However, most drug subs so far are not as sophisticated as professional merchant submarines would be, being mainly intended to run just under the surface, rather than deeply submerged.

See also

  • Amphibious assault submarine
    Amphibious assault submarine
    An amphibious assault submarine is a so far theoretical submarine equivalent of an amphibious assault ship. While such ships have been proposed in the past by both the U.S. and the Soviet Union, none has ever been built...

  • Submarine Cargo Vessel
    Submarine Cargo Vessel
    The Submarine Cargo Vessel is a proposed idea from the Russian Rubin Design Bureau. The idea is to utilise decommissioned SSBNs from the Russian Navy to carry cargo under the Arctic Ocean...

  • Defensively Equipped Merchant Ships
    Defensively Equipped Merchant Ships
    Defensively Equipped Merchant Ship was an Admiralty Trade Division program established in June, 1939, to arm 5,500 British merchant ships with an adequate defence against enemy submarines and aircraft...

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.