Tonnage war
Encyclopedia
A tonnage war is a military strategy
aimed at merchant shipping. The premise is that an enemy has only a finite number of ship
s, and a finite capacity to build replacements for them. The concept was made famous by U-boat
commander 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...
Most anti-shipping strategies primarily aim at a relatively narrow set of goals. For example, a traditional practice of the Royal Navy
during wars between Britain and France
was blockade
. By concentrating available naval units forces near the major French ports, the Royal Navy was usually able to strangle French trade and create significant economic difficulties. Similarly, an enemy may focus on ships carrying strategically vital cargos such as hemp
and timber
or, in modern times, oil
and iron
. Alternatively, the aim may be to target ships carrying particularly valuable cargos such as treasure or munitions, and ships carrying less critical cargoes or steaming in ballast
are assigned a lower priority.
In general, these relatively narrow strategies require that the attacker establish substantial control over a particular area. For example, the British blockades of France were only possible so long as the Royal Navy retained the ability to defeat any French squadron venturing out from port to make a challenge. Similarly, during the early part of World War II
, Axis
air forces controlled the Mediterranean and were able to prevent many Allied ships from reaching Malta
with supplies and were almost successful in reducing the island fortress.
A tonnage war, however, is a very broad strategy, and does not require that the attacker establish control over any particular area, merely that he is able to sink ships more rapidly than the defender can replace them.
During the Second World War, three tonnage wars were fought. The largest and best known of them was Dönitz's U-boat campaign, aimed mainly against the United Kingdom. Although the primary venue for the campaign
was the North Atlantic, Dönitz sent U-boat
s and surface raiders to all corners of the globe in search of the most efficient way to sink the maximum number of ships at minimum cost. The U-boats campaign was very successful especially in the two happy periods (in 1940
and in 1942
), and was able to reduce the total shipping available to the Allies up to a breakage point until 1943, when the tide of war was turning against Germany. On the other side, important factor in the British anti-submarine effort was the success of the codebreakers at Bletchley Park
in reading messages encrypted using the German Enigma machine
.
Less well-known were two campaigns by Allied forces, neither of them deliberately planned as a tonnage war in the way that Dönitz's U-boat campaign was, but both having that effect—and both were also very successful. The first of these was the Allied campaign against Axis shipping (mostly Italian
) from Europe
to North Africa
. British submarines based in Malta and the aircraft of several Allied air forces, in conjunction with British and Commonwealth
surface ships, succeeded in reducing shipments of essential military supplies to Axis forces under Rommel
to the point where the German commander was unable to fight effectively. By the close of the campaign, Italy had very few merchant ships left.
In the early years of the Pacific War
, the submarines of the US Navy were allocated a great variety of tasks and were unable to achieve any of them effectively, particularly given major technical problems with the Mark 14 torpedo
es they were armed with. From about the middle of 1943, however, substantial numbers of American submarine
s were tasked with disrupting Japan
ese trade, in particular, with cutting off the flow of oil and other vital materials from the occupied territories of South-east Asia. This, too, became a tonnage war, with rapidly building results, and by mid to late 1944 Allied submarines and aircraft were experiencing difficulty in finding targets large enough to justify expending a torpedo on. The Japanese merchant navy was all but wiped out, and despite desperate measures to make do without strategic materials, the war economy ground to a virtual standstill.
Military strategy
Military strategy is a set of ideas implemented by military organizations to pursue desired strategic goals. Derived from the Greek strategos, strategy when it appeared in use during the 18th century, was seen in its narrow sense as the "art of the general", 'the art of arrangement' of troops...
aimed at merchant shipping. The premise is that an enemy has only a finite number of ship
Ship
Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...
s, and a finite capacity to build replacements for them. The concept was made famous by U-boat
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...
commander Karl Dönitz
Karl Dönitz
Karl Dönitz was a German naval commander during World War II. He started his career in the German Navy during World War I. In 1918, while he was in command of , the submarine was sunk by British forces and Dönitz was taken prisoner...
, 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...
Most anti-shipping strategies primarily aim at a relatively narrow set of goals. For example, a traditional practice of the 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...
during wars between Britain and France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
was blockade
Blockade
A blockade is an effort to cut off food, supplies, war material or communications from a particular area by force, either in part or totally. A blockade should not be confused with an embargo or sanctions, which are legal barriers to trade, and is distinct from a siege in that a blockade is usually...
. By concentrating available naval units forces near the major French ports, the Royal Navy was usually able to strangle French trade and create significant economic difficulties. Similarly, an enemy may focus on ships carrying strategically vital cargos such as hemp
Hemp
Hemp is mostly used as a name for low tetrahydrocannabinol strains of the plant Cannabis sativa, of fiber and/or oilseed varieties. In modern times, hemp has been used for industrial purposes including paper, textiles, biodegradable plastics, construction, health food and fuel with modest...
and timber
Timber
Timber may refer to:* Timber, a term common in the United Kingdom and Australia for wood materials * Timber, Oregon, an unincorporated community in the U.S...
or, in modern times, oil
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...
and iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
. Alternatively, the aim may be to target ships carrying particularly valuable cargos such as treasure or munitions, and ships carrying less critical cargoes or steaming in ballast
Sailing ballast
Ballast is used in sailboats to provide moment to resist the lateral forces on the sail. Insufficiently ballasted boats will tend to tip, or heel, excessively in high winds. Too much heel may result in the boat capsizing. If a sailing vessel should need to voyage without cargo then ballast of...
are assigned a lower priority.
In general, these relatively narrow strategies require that the attacker establish substantial control over a particular area. For example, the British blockades of France were only possible so long as the Royal Navy retained the ability to defeat any French squadron venturing out from port to make a challenge. Similarly, during the early part of World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
, 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...
air forces controlled the Mediterranean and were able to prevent many Allied ships from reaching Malta
Malta
Malta , officially known as the Republic of Malta , is a Southern European country consisting of an archipelago situated in the centre of the Mediterranean, south of Sicily, east of Tunisia and north of Libya, with Gibraltar to the west and Alexandria to the east.Malta covers just over in...
with supplies and were almost successful in reducing the island fortress.
A tonnage war, however, is a very broad strategy, and does not require that the attacker establish control over any particular area, merely that he is able to sink ships more rapidly than the defender can replace them.
World War II
Second Battle of the Atlantic
The Battle of the Atlantic was the longest continuous military campaign in World War II, running from 1939 to the defeat of Germany in 1945. At its core was the Allied naval blockade of Germany, announced the day after the declaration of war, and Germany's subsequent counter-blockade. It was at its...
was the North Atlantic, Dönitz sent U-boat
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 and surface raiders to all corners of the globe in search of the most efficient way to sink the maximum number of ships at minimum cost. The U-boats campaign was very successful especially in the two happy periods (in 1940
First Happy Time
The First Happy Time was a phase of the Battle of the Atlantic during which Germany Navy U-boats enjoyed significant success against the British Royal Navy and its allies...
and in 1942
Second happy time
The Second Happy Time , also known among German submarine commanders as the "American shooting season" was the informal name for a phase in the Second Battle of the Atlantic during which Axis submarines attacked merchant shipping along the east coast of North America...
), and was able to reduce the total shipping available to the Allies up to a breakage point until 1943, when the tide of war was turning against Germany. On the other side, important factor in the British anti-submarine effort was the success of the codebreakers at Bletchley Park
Bletchley Park
Bletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Museum of Computing...
in reading messages encrypted using the German Enigma machine
Enigma machine
An Enigma machine is any of a family of related electro-mechanical rotor cipher machines used for the encryption and decryption of secret messages. Enigma was invented by German engineer Arthur Scherbius at the end of World War I...
.
Less well-known were two campaigns by Allied forces, neither of them deliberately planned as a tonnage war in the way that Dönitz's U-boat campaign was, but both having that effect—and both were also very successful. The first of these was the Allied campaign against Axis shipping (mostly Italian
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
) from Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
to North Africa
North Africa
North Africa or Northern Africa is the northernmost region of the African continent, linked by the Sahara to Sub-Saharan Africa. Geopolitically, the United Nations definition of Northern Africa includes eight countries or territories; Algeria, Egypt, Libya, Morocco, South Sudan, Sudan, Tunisia, and...
. British submarines based in Malta and the aircraft of several Allied air forces, in conjunction with British and Commonwealth
Commonwealth of Nations
The Commonwealth of Nations, normally referred to as the Commonwealth and formerly known as the British Commonwealth, is an intergovernmental organisation of fifty-four independent member states...
surface ships, succeeded in reducing shipments of essential military supplies to Axis forces under Rommel
Rommel
Erwin Rommel was a German World War II field marshal.Rommel may also refer to:*Rommel *Rommel Adducul , Filipino basketball player*Rommel Fernández , first Panamanian footballer to play in Europe...
to the point where the German commander was unable to fight effectively. By the close of the campaign, Italy had very few merchant ships left.
In the early years of the Pacific War
Pacific War
The Pacific War, also sometimes called the Asia-Pacific War refers broadly to the parts of World War II that took place in the Pacific Ocean, its islands, and in East Asia, then called the Far East...
, the submarines of the US Navy were allocated a great variety of tasks and were unable to achieve any of them effectively, particularly given major technical problems with the Mark 14 torpedo
Mark 14 torpedo
The Mark 14 torpedo was the United States Navy's standard submarine-launched anti-ship torpedo of World War II.This weapon was plagued with many problems which crippled its performance early in the war, and was supplemented by the Mark 18 electric torpedo in the last 2 years of the war...
es they were armed with. From about the middle of 1943, however, substantial numbers of American submarine
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...
s were tasked with disrupting Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
ese trade, in particular, with cutting off the flow of oil and other vital materials from the occupied territories of South-east Asia. This, too, became a tonnage war, with rapidly building results, and by mid to late 1944 Allied submarines and aircraft were experiencing difficulty in finding targets large enough to justify expending a torpedo on. The Japanese merchant navy was all but wiped out, and despite desperate measures to make do without strategic materials, the war economy ground to a virtual standstill.
See also
- Naval strategyNaval strategyNaval strategy is the planning and conduct of war at sea, the naval equivalent of military strategy on land.Naval strategy, and the related concept of maritime strategy, concerns the overall strategy for achieving victory at sea, including the planning and conduct of campaigns, the movement and...
- Commerce raidingCommerce raidingCommerce raiding or guerre de course is a form of naval warfare used to destroy or disrupt the logistics of an enemy on the open sea by attacking its merchant shipping, rather than engaging the combatants themselves or enforcing a blockade against them.Commerce raiding was heavily criticised by...
- Unrestricted submarine warfareUnrestricted submarine warfareUnrestricted submarine warfare is a type of naval warfare in which submarines sink merchantmen without warning, as opposed to attacks per prize rules...
- Merchant raiderMerchant raiderMerchant raiders are ships which disguise themselves as non-combatant merchant vessels, whilst actually being armed and intending to attack enemy commerce. Germany used several merchant raiders early in World War I, and again early in World War II...