Allied submarines in the Pacific War

Allies of World War II

The Allies of World War II were the countries that opposed the Axis powers during the Second World War . Former Axis states contributing to the Allied victory are not considered Allied states...

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 used extensively during 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...

and were a key contributor to the defeat of the Empire of Japan

Empire of Japan

The Empire of Japan is the name of the state of Japan that existed from the Meiji Restoration on 3 January 1868 to the enactment of the post-World War II Constitution of...

. During the war, submarines of the United States Navy

United States Navy

The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

were responsible for 55% of Japan's merchant marine

Ship transport

Ship transport is watercraft carrying people or goods . Sea transport has been the largest carrier of freight throughout recorded history. Although the importance of sea travel for passengers has decreased due to aviation, it is effective for short trips and pleasure cruises...

losses; other Allied navies added to the toll. The war against shipping was the single most decisive factor in the collapse of the Japanese economy. Allied submarines also conducted reconnaissance patrols, landed special forces

Special forces

Special forces, or special operations forces are terms used to describe elite military tactical teams trained to perform high-risk dangerous missions that conventional units cannot perform...

and guerrilla

Guerrilla warfare

Guerrilla warfare is a form of irregular warfare and refers to conflicts in which a small group of combatants including, but not limited to, armed civilians use military tactics, such as ambushes, sabotage, raids, the element of surprise, and extraordinary mobility to harass a larger and...

troops and performed search and rescue

Search and rescue

Search and rescue is the search for and provision of aid to people who are in distress or imminent danger.The general field of search and rescue includes many specialty sub-fields, mostly based upon terrain considerations...

tasks. The majority of the submarines involved were from the U.S. Navy, with the British 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...

and the Royal Netherlands Navy

Royal Netherlands Navy

The Koninklijke Marine is the navy of the Netherlands. In the mid-17th century the Dutch Navy was the most powerful navy in the world and it played an active role in the wars of the Dutch Republic and later those of the Batavian Republic and the Kingdom of the Netherlands...

contributing smaller numbers of boats.

The Allied submarine campaign is one of the least-publicized feats in military history

Military history

Military history is a humanities discipline within the scope of general historical recording of armed conflict in the history of humanity, and its impact on the societies, their cultures, economies and changing intra and international relationships....

, due in large part to the efforts of Allied governments to ensure their own submarines' actions were not reported in the media. The U.S. Navy adopted an official policy of unrestricted submarine warfare

Unrestricted submarine warfare

Unrestricted submarine warfare is a type of naval warfare in which submarines sink merchantmen without warning, as opposed to attacks per prize rules...

, and it appears the policy was executed without the knowledge or prior consent of the government. The London Naval Treaty

London Naval Treaty

The London Naval Treaty was an agreement between the United Kingdom, the Empire of Japan, France, Italy and the United States, signed on April 22, 1930, which regulated submarine warfare and limited naval shipbuilding. Ratifications were exchanged in London on October 27, 1930, and the treaty went...

, to which the U.S. was signatory. required submarines to abide by prize rules (commonly known as "cruiser rules"). It did not prohibit arming merchantmen, but arming them, or having them report contact with submarines (or raiders

Commerce raiding

Commerce 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...

), made them de facto naval auxiliaries and removed the protection of the cruiser rules. This made restrictions on submarines effectively moot. While the Allies were conducting a massive propaganda campaign against the actions of German 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, their own submarines were operating exactly as the Germans did.

Strategic implications

Throughout the war, Japan was dependent on sea transport to provide adequate resources, including food, to the home islands

Japanese Archipelago

The , which forms the country of Japan, extends roughly from northeast to southwest along the northeastern coast of the Eurasia mainland, washing upon the northwestern shores of the Pacific Ocean...

and supply its military at garrisons across the Pacific. Before the war, Japan estimated the nation required 5900000 LT (5,994,695 t) of shipping to maintain the domestic economy and military during a major war, which was considerably less than the 6400000 LT (6,502,720 t) of shipping in the Japanese merchant fleet and 1200000 LT (1,219,260 t) of smaller craft at the time of the attack on Pearl Harbor

Attack on Pearl Harbor

The attack on Pearl Harbor was a surprise military strike conducted by the Imperial Japanese Navy against the United States naval base at Pearl Harbor, Hawaii, on the morning of December 7, 1941...

. Despite the awareness shipping was vital, the Japanese military accorded anti-submarine warfare

Anti-submarine warfare

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

a low priority and allocated few warships and aircraft to protecting merchant shipping For instance, their destroyers had deficiencies in sonar and radar compared to equivalents of other navies, despite their impressive night fighting capabilities, even though these warships formed the bulk of convoy protection. Moreover, Japanese Navy

Imperial Japanese Navy

The Imperial Japanese Navy was the navy of the Empire of Japan from 1869 until 1947, when it was dissolved following Japan's constitutional renunciation of the use of force as a means of settling international disputes...

doctrine in relation to commerce defense

Convoy

A convoy is a group of vehicles, typically motor vehicles or ships, traveling together for mutual support and protection. Often, a convoy is organized with armed defensive support, though it may also be used in a non-military sense, for example when driving through remote areas.-Age of Sail:Naval...

was derisively bad. The Japanese also seriously underestimated the threat from Allied submarines, whose ineffectiveness in the early part of the war reinforced Japanese overconfidence.

The size and effectiveness of the Allied submarine force increased greatly during the Pacific War. At the start of the war, a high proportion of the submarines deployed against the Japanese were obsolete, and U.S. boats were hampered by defects in their primary weapon, 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...

, as well as by poor training (an excessive reliance on sonar

Sonar

Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...

, due to an undue fear of destroyer

Destroyer

In naval terminology, a destroyer is a fast and maneuverable yet long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against smaller, powerful, short-range attackers. Destroyers, originally called torpedo-boat destroyers in 1892, evolved from...

s' sonar and aircraft), insufficiently aggressive skippers, poor dispositions (scattered on close surveillance of Japan's major bases), and divided command (which kept submarines out of one of the best hunting areas, the Luzon Strait

Luzon Strait

The Luzon Strait is the strait between the island country of Taiwan and Luzon island of the Philippines. The strait thereby connects the Philippine Sea to the South China Sea in the western Pacific Ocean....

, for fear of fratricide

Fratricide

Fratricide is the act of a person killing his or her brother....

). Growing numbers of modern submarines became available from 1942 onwards. The efforts of Admiral Charles A. Lockwood

Charles A. Lockwood

Charles Andrews Lockwood was an admiral of the United States Navy. He is known in submarine history as the legendary commander of Submarine Force Pacific Fleet during World War II...

were crucial for the rectification of the Mark 14's problems (which were nevertheless not resolved until September 1943), and for the selection of more aggressive submarine skippers. As a result of all of these developments, assisted by signals intelligence (breaking the "maru code" in January 1943, after a gaffe by U.S. Customs prewar had caused Japan to change it), U.S. submarines inflicted devastating losses on Japanese merchant shipping in 1943 and 1944. In conjunction with attacks by aircraft, including aerial minelaying, U.S. submarines had effectively destroyed the Japanese merchant fleet by January 1945. Poor torpedoes claimed at least two U.S. submarines out of 42 lost in action.

Prelude

The U.S. had the largest and most powerful submarine force of all the Allied countries in the Pacific at the outbreak of war. Pre-war U.S. Navy doctrine—like that of all major navies—specified the main role of submarines was to support the surface fleet by conducting reconnaissance and attacking large enemy warships. Merchant ships were regarded as secondary targets, and the circumstances in which they could be attacked were greatly limited by prize rules set out in the London Naval Treaty

London Naval Treaty

, to which the U.S. was a signatory. In order to meet their role with the surface fleet the U.S. Navy built large submarines which boasted long range, a relatively fast cruising speed and a heavy armament of torpedo

Torpedo

The modern torpedo is a self-propelled missile 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 it or in proximity to it.The term torpedo was originally employed for...

s. U.S. submarine habitability was greatly enhanced by air conditioning

Air conditioning

An air conditioner is a home appliance, system, or mechanism designed to dehumidify and extract heat from an area. The cooling is done using a simple refrigeration cycle...

(which German U-boat

U-boat

s, for instance, lacked) and water distilleries

Distillation

Distillation is a method of separating mixtures based on differences in volatilities of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....

, and were more comfortable, hence better suited to long patrols in the tropics

Tropics

The tropics is a region of the Earth surrounding the Equator. It is limited in latitude by the Tropic of Cancer in the northern hemisphere at approximately N and the Tropic of Capricorn in the southern hemisphere at S; these latitudes correspond to the axial tilt of the Earth...

, than those of the other major powers. The submarines' commanders and crewmen were considered an elite and enjoyed a strong esprit. On 7 December 1941, the USN had 55 fleet and 18-medium sized submarines (S-boats

United States S class submarine

The United States' S-class submarines, often simply called S-boats , were the first class of submarines built to a United States Navy design....

) in the Pacific, 38 submarines elsewhere, and 73 under construction. (By war's end, the U.S. would complete 228 submarines.)

While Britain

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

stationed a force of submarines in the Far East prior to the outbreak of war, none were available in December 1941. The British had 15 modern submarines in the Far East in September 1939. These submarines formed part of the China Station

China Station

The China Station was a historical formation of the British Royal Navy. It was formally the units and establishments responsible to the Commander-in-Chief, China....

and were organised into the 4th Flotilla. Although the number of British submarines in the Far East increased in early 1940 when the 8th Flotilla arrived at Ceylon, both flotilla

Flotilla

A flotilla , or naval flotilla, is a formation of small warships that may be part of a larger fleet. A flotilla is usually composed of a homogeneous group of the same class of warship, such as frigates, destroyers, torpedo boats, submarines, gunboats, or minesweepers...

s and all their submarines were withdrawn in mid-1940 to reinforce the Mediterranean Fleet

Mediterranean Fleet

Several countries have or have had a Mediterranean Fleet in their navy. See:* Mediterranean Fleet * French Mediterranean Fleet* Mediterranean Squadron * United States Sixth Fleet...

.

The Netherlands

Netherlands

The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

also maintained a submarine force in the Far East in order to protect the Netherlands East Indies (NEI). In December 1941, this force comprised 15 boats based at Surabaya

Surabaya

Surabaya is Indonesia's second-largest city with a population of over 2.7 million , and the capital of the province of East Java...

, most of which were obsolete.

Countering the Japanese offensive

In a break with pre-war doctrine (which, like Japan's, had presumed a rush across the Pacific and a "decisive battle" between battleship

Battleship

A battleship is a large armored warship with a main battery consisting of heavy caliber guns. Battleships were larger, better armed and armored than cruisers and destroyers. As the largest armed ships in a fleet, battleships were used to attain command of the sea and represented the apex of a...

s) with the London Naval Treaty, and with long-standing U.S. defense of freedom of the seas

Freedom of the seas

Freedom of the seas is a principle in the international law and law of the sea. It stresses freedom to navigate the oceans. It also disapproves of war fought in water. The freedom is to be breached only in a necessary international agreement....

, U.S. naval commanders in the Pacific were ordered to "execute unrestricted air and submarine warfare against Japan" on the afternoon of 7 December 1941, a mere six hours after the Japanese attack; Hart—on his own initiative (but knowing Stark

Harold Rainsford Stark

Harold Rainsford Stark served as an officer in the United States Navy during World War I and World War II. Stark was the US Navy's 8th Chief of Naval Operations, from August 1, 1939 to 26 March 1942....

intended to do so)—issued the same order at 03:45 Manila time (09:15 in Hawaii, 14:45 in DC). The Pacific Fleet

United States Pacific Fleet

The United States Pacific Fleet is a Pacific Ocean theater-level component command of the United States Navy that provides naval resources under the operational control of the United States Pacific Command. Its home port is at Pearl Harbor Naval Base, Hawaii. It is commanded by Admiral Patrick M...

Submarine Force had emerged unscathed from the attack on Pearl Harbor and departed on the fleet's first offensive war patrol on 11 December. The Asiatic Fleet

United States Asiatic Fleet

The United States Asiatic Fleet was part of the U.S. Navy. Preceding the World War II era, until 1942, the fleet protected the Philippines.Originally the Asiatic Squadron, it was upgraded to fleet status in 1902. In 1907, the fleet became the First Squadron of the Pacific Fleet. However, on 28...

's 27 submarines (including more fleet boats than at Pearl Harbor) also went into action on the first day of the war, beginning war patrols in the waters around the Philippines

Philippines

The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...

and Indochina

Indochina

The Indochinese peninsula, is a region in Southeast Asia. It lies roughly southwest of China, and east of India. The name has its origins in the French, Indochine, as a combination of the names of "China" and "India", and was adopted when French colonizers in Vietnam began expanding their territory...

. Thanks to inadequate prewar planning, which made no provision for defensive minelaying

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...

, nor placing submarines on station around the Philippines, nor off enemy harbors, the Asiatic Fleet's efforts to counter the Japanese invasion of the Philippines were unsuccessful and the Fleet's surviving submarines were forced to withdraw to Surabaya

Surabaya

Surabaya is Indonesia's second-largest city with a population of over 2.7 million , and the capital of the province of East Java...

in the Dutch East Indies

Dutch East Indies

The Dutch East Indies was a Dutch colony that became modern Indonesia following World War II. It was formed from the nationalised colonies of the Dutch East India Company, which came under the administration of the Netherlands government in 1800....

(DEI).

British, Dutch, and U.S. submarines took part in the unsuccessful defense of British Malaya and the DEI in late 1941 and early 1942. In December 1941, five Dutch submarines attacked the Japanese invasion fleet off Malaya

Battle of Malaya

The Malayan Campaign was a campaign fought by Allied and Japanese forces in Malaya, from 8 December 1941 – 31 January 1942 during the Second World War. The campaign was dominated by land battles between British Commonwealth army units, and the Imperial Japanese Army...

. These submarines sank two Japanese merchant ships and damaged four others, but three of the attackers were sunk. The two surviving Dutch submarines were withdrawn to defend the DEI where they were assisted by two British submarines, which had been transferred from the Mediterranean Fleet, and several U.S. boats. The U.S. Asiatic Fleet's submarine force left Surabaya for Fremantle

Fremantle, Western Australia

Fremantle is a city in Western Australia, located at the mouth of the Swan River. Fremantle Harbour serves as the port of Perth, the state capital. Fremantle was the first area settled by the Swan River colonists in 1829...

in Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

on 1 March. (They would remain in Australia, on the most hazardous and unproductive stations for U.S. submarines, for the duration.) By this date, the Asiatic Fleet's 27 submarines had sunk only 12 Japanese ships for the loss of four U.S. boats. Following the fall of the DEI, only a handful of British and Dutch submarines were based in the Indian Ocean

Indian Ocean

The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

, and these had little impact on Japanese forces in the area.

War of attrition

After the Battle of Coral Sea, the U.S. Navy detached eight submarines to finish off the damaged aircraft carrier

Aircraft carrier

An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power worldwide without having to depend on local bases for staging aircraft operations...

, but she evaded all of them. At the Battle of Midway

Battle of Midway

The Battle of Midway is widely regarded as the most important naval battle of the Pacific Campaign of World War II. Between 4 and 7 June 1942, approximately one month after the Battle of the Coral Sea and six months after Japan's attack on Pearl Harbor, the United States Navy decisively defeated...

, although the attack on the battleship

Battleship

by had been unsuccessful, it drew the destroyer Arashi temporarily away from the main fleet to drop depth charges, and the destroyer's return was traced by 's VB-6 to the Japanese task force, where the dive bombers promptly sank four fleet carriers. Overall in 1942, U.S. submarines had only managed to sink the heavy cruiser

Heavy cruiser

The heavy cruiser was a type of cruiser, a naval warship designed for long range, high speed and an armament of naval guns roughly 203mm calibre . The heavy cruiser can be seen as a lineage of ship design from 1915 until 1945, although the term 'heavy cruiser' only came into formal use in 1930...

and the light cruiser

Light cruiser

A light cruiser is a type of small- or medium-sized warship. The term is a shortening of the phrase "light armored cruiser", describing a small ship that carried armor in the same way as an armored cruiser: a protective belt and deck...

.

As a result of several key improvements the previous year, U.S. submarines inflicted tremendous losses to the heavy units of the Imperial Japanese Navy in 1944. They destroyed the Japanese fleet carriers Shōkaku and in the Battle of the Philippine Sea

Battle of the Philippine Sea

The Battle of the Philippine Sea was a decisive naval battle of World War II which effectively eliminated the Imperial Japanese Navy's ability to conduct large-scale carrier actions. It took place during the United States' amphibious invasion of the Mariana Islands during the Pacific War...

, and sank or disabled three Takao-class

Takao class cruiser

- Notes :...

cruisers at the start of the Battle of Leyte Gulf. Also sunk that year were the battleship and the carrier , the latter being the largest vessel ever lost to submarine torpedoes.

From 1943, Allied submarines waged an increasingly effective campaign against Japanese merchant shipping and the IJN. By the end of the war in August 1945, the Japanese merchant marine had less than a quarter of the tonnage it had in December 1941. Overall, U.S. Navy submarines sank around 1300 Japanese merchant ships, as well as roughly 200 warships. Despite the need to maintain sea lanes for its empire, the Japanese never successfully developed a cost-effective destroyer escort

Destroyer escort

A destroyer escort is the classification for a smaller, lightly armed warship designed to be used to escort convoys of merchant marine ships, primarily of the United States Merchant Marine in World War II. It is employed primarily for anti-submarine warfare, but also provides some protection...

better suited for convoy duties, while it also did not have the industrial-military complex to replace the losses of its heavily-armed destroyers, nor of its ill-protected merchantmen.

British and Dutch submarine operations

The British submarine force in the Far East was greatly expanded from August 1943. The British Eastern Fleet was responsible for submarine operations in the Bay of Bengal

Bay of Bengal

The Bay of Bengal , the largest bay in the world, forms the northeastern part of the Indian Ocean. It resembles a triangle in shape, and is bordered mostly by the Eastern Coast of India, southern coast of Bangladesh and Sri Lanka to the west and Burma and the Andaman and Nicobar Islands to the...

, Strait of Malacca

Strait of Malacca

The Strait of Malacca is a narrow, stretch of water between the Malay Peninsula and the Indonesian island of Sumatra. It is named after the Malacca Sultanate that ruled over the archipelago between 1414 to 1511.-Extent:...

as far as Singapore, and the western coast of Sumatra

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...

to the Equator. Few large Japanese cargo ships operated in this area, and the British submarines' main targets were small craft operating in inshore waters. The submarines were deployed to conduct reconnaissance, interdict Japanese supplies travelling to Burma, and attack U-boats operating from Penang. The Eastern Fleet's submarine force continued to expand during 1944, and by October 1944 had sunk a cruiser, three submarines, six small naval vessels, 40000 LT (40,642 t) of merchant ships, and nearly 100 small vessels.

The British submarine force expanded its areas of operation in the last months of the war. In late 1944, the Eighth Flotilla—with 11 British and Dutch submarines—was transferred to Fremantle and operated in the Java Sea

Java Sea

The Java Sea is a large shallow sea on the Sunda Shelf. It was formed as sea levels rose at the end of the last ice age. The Java Sea lies between the Indonesian islands of Borneo to the north, Java to the south; Sumatra to the west, and Sulawesi to the east...

and surrounding areas under the command of the U.S 7th Fleet

United States Seventh Fleet

The Seventh Fleet is the United States Navy's permanent forward projection force based in Yokosuka, Japan, with units positioned near Japan and South Korea. It is a component fleet force under the United States Pacific Fleet. At present, it is the largest of the forward-deployed U.S. fleets, with...

. The Fourth Flotilla and the newly-formed Second Flotilla remained at Ceylon. By March 1945, British boats had gained control of the Strait of Malacca, preventing any supplies from reaching the Japanese forces in Burma by sea. By this time, there were few large Japanese ships in the region, and the submarines mainly operated against small ships which they attacked with their deck guns. In April the Eighth Flotilla moved to Subic Bay

Subic Bay

Subic Bay is a bay forming part of Luzon Sea on the west coast of the island of Luzon in Zambales, Philippines, about 100 kilometers northwest of Manila Bay. Its shores were formerly the site of a major United States Navy facility named U.S...

in the Philippines and the Fourth Flotilla replaced it at Fremantle. At this time, there were 38 British and Dutch submarines in the theater, and an additional five boats on their way from Europe. The submarine torpedoed and sank the heavy cruiser in the Bangka Strait

Bangka Strait

Bangka Strait is a strait which separates the island of Sumatra and Bangka Island in the Java Sea, Indonesia.-See also:* Japanese cruiser Ashigara* List of straits...

, taking down some 1,200 Japanese army troops.

Three British submarines were sunk by the Japanese during the war.

Merchant shipping losses

As figures for the size of the Japanese merchant marine and its losses differ between different sources, it is impossible to provide a definitive accounting of the state of the merchant marine over the course of the war. The following tables show different assessments of Japanese losses and construction.

Size of the Japanese merchant fleet during World War II (all figures in tons)

Date	Additions	Losses	Net change	End of period total	Index
12/07/1941				6,384,000	100
12/1941	44,200	51,600	-7,400	6,376,600	99
1942	661,800	1,095,800	-434,000	5,942,600	93
1943	1,067,100	2,065,700	-998,600	4,494,400	77
1944	1,735,100	4,115,100	-2,380,000	2,564,000	40
1/45 - 8/45	465,000	1,562,100	-1,097,100	1,466,900	23

Japanese merchant fleet losses during World War II (all figures in tons, taken from JANAC

Joint Army-Navy Assessment Committee

Joint Army-Navy Assessment Committee was a United States inter-service agency set up to analyze and assess Japanese naval and merchant marine shipping losses caused by U.S. and Allied forces during World War II.-Background:...

)

Date	Starting tonnage	Additions	Losses	Net change	End of period total
1942 (including 12/41)	5,975,000	111,000	725,000	-89,000	5,886,000
1943	5,886,000	177,000	1,500,000	-1,323,000	4,963,000
1944	4,963,000	624,000	2,700,000	-2,076,000	2,887,000
1945	2,887,000	?	415,000	-415,000	2,472,000
end of war
1,983,000

One Japanese reference reports 15,518 civilian ships lost. JANAC reports 2,117 Japanese merchant ships lost with a total tonnage of 7913858 LT (8,040,875.4 t) and 611 IJN ships lost with a total tonnage of 1822210 LT (1,851,456.5 t).

Other duties

Allied submarines served in a range of other duties during the Pacific War. U.S. Navy submarines were often used for surveillance. This included taking photos of areas of interest (such as potential beaches for amphibious landings

Amphibious warfare

Amphibious warfare is the use of naval firepower, logistics and strategy to project military power ashore. In previous eras it stood as the primary method of delivering troops to non-contiguous enemy-held terrain...

), and reporting on the movements of IJN warships. U.S. submarines landed and supplied reconnaissance and guerrilla forces and played a role in sustaining the guerrilla movement in the Philippines, at the cost of their diversion from productive use in attacks on Japanese commerce. They also occasionally transported commando

Commando

In English, the term commando means a specific kind of individual soldier or military unit. In contemporary usage, commando usually means elite light infantry and/or special operations forces units, specializing in amphibious landings, parachuting, rappelling and similar techniques, to conduct and...

s, such as Nautilus and landing Marine Raiders

Marine Raiders

The Marine Raiders were elite units established by the United States Marine Corps during World War II to conduct amphibious light infantry warfare, particularly in landing in rubber boats and operating behind the lines...

for an abortive raid on Makin Atoll

Butaritari

Butaritari is an atoll located in the Pacific Ocean island nation of Kiribati.-Geography:...

. From early 1944 U.S. submarines were also used to rescue the crews of aircraft which had been forced down over the ocean. By the end of the war, submarines had rescued 504 airmen (including George H. W. Bush

George H. W. Bush

George Herbert Walker Bush is an American politician who served as the 41st President of the United States . He had previously served as the 43rd Vice President of the United States , a congressman, an ambassador, and Director of Central Intelligence.Bush was born in Milton, Massachusetts, to...

, who later became the 41st President of the United States

President of the United States

The President of the United States of America is the head of state and head of government of the United States. The president leads the executive branch of the federal government and is the commander-in-chief of the United States Armed Forces....

). British and Dutch submarines also landed and supplied special forces

Special forces

Special forces, or special operations forces are terms used to describe elite military tactical teams trained to perform high-risk dangerous missions that conventional units cannot perform...

troops, rescued airmen, and shelled shore installations on nine occasions.

Britain also deployed a flotilla of midget submarine

Midget submarine

A midget submarine is any submarine under 150 tons, typically operated by a crew of one or two but sometimes up to 6 or 8, with little or no on-board living accommodation...

s to the Far East which were used to conduct sabotage raids. The Fourteenth Flotilla, which was equipped with six XE-class submarines

XE class submarine

Six XE-class midget submarines were built for the Royal Navy during 1944. They were an improved version of the X Class midgets used in the attack on the German battleship Tirpitz....

, arrived in Australia in April 1945 but was almost disbanded in May as no suitable targets could be found. The Flotilla's fortunes improved in early June, however, when undersea telegraph lines in the South China Sea were identified as being worthwhile targets along with a heavy cruiser

Heavy cruiser

at Singapore. On 31 July, XE4

XE class submarine

Six XE-class midget submarines were built for the Royal Navy during 1944. They were an improved version of the X Class midgets used in the attack on the German battleship Tirpitz....

cut the submerged Singapore-Saigon telegraph cable near Cape St. Jacques in French Indochina

French Indochina

French Indochina was part of the French colonial empire in southeast Asia. A federation of the three Vietnamese regions, Tonkin , Annam , and Cochinchina , as well as Cambodia, was formed in 1887....

and XE5

XE class submarine

Six XE-class midget submarines were built for the Royal Navy during 1944. They were an improved version of the X Class midgets used in the attack on the German battleship Tirpitz....

cut the Hong Kong-Saigon cable close to Lamma Island

Lamma Island

Lamma Island , also known as Pok Liu Chau or simply Pok Liu , is the third largest island in Hong Kong. Administratively, it is part of the Islands District.-Name:...

, Hong Kong

Hong Kong

Hong Kong is one of two Special Administrative Regions of the People's Republic of China , the other being Macau. A city-state situated on China's south coast and enclosed by the Pearl River Delta and South China Sea, it is renowned for its expansive skyline and deep natural harbour...

. At the same time, XE1

XE class submarine

Six XE-class midget submarines were built for the Royal Navy during 1944. They were an improved version of the X Class midgets used in the attack on the German battleship Tirpitz....

and XE3

XE class submarine

Six XE-class midget submarines were built for the Royal Navy during 1944. They were an improved version of the X Class midgets used in the attack on the German battleship Tirpitz....

penetrated the Straits of Johor

Straits of Johor

The Straits of Johor is a strait that separates the Malaysian state of Johor to the north from Singapore to the south....

where they severely damaged the Japanese heavy cruiser with limpet mine

Limpet mine

A limpet mine is a type of naval mine attached to a target by magnets; they are so named because of their superficial similarity to the limpet, a type of mollusk....

Post-war

Allied actions in the Pacific are believed to have been a mitigating factor in reducing the sentence of Großadmiral 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...

following the Nuremberg Trials

Nuremberg Trials

The Nuremberg Trials were a series of military tribunals, held by the victorious Allied forces of World War II, most notable for the prosecution of prominent members of the political, military, and economic leadership of the defeated Nazi Germany....

, who was accused of similar actions in the Battle of the Atlantic; indeed, Admiral Nimitz provided Dönitz with a statement saying his boats behaved no differently.

External links

Combined Fleet Website

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