Allied submarines were used extensively during the Pacific War and were a key contributor to the defeat of the Empire of Japan.
The Allies of World War II, called the "United Nations" from the 1 January 1942 declaration, were the countries that together opposed the Axis powers during the Second World War (1939–1945). The Allies promoted the alliance as a means to control German, Japanese and Italian aggression.
A submarine is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. 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 Pacific War, sometimes called the Asia–Pacific War, was the theater of World War II that was fought in the Pacific and Asia. It was fought over a vast area that included the Pacific Ocean and islands, the South West Pacific, South-East Asia, and in China.
During the war, submarines of the United States Navy were responsible for 55% of Japan's merchant marine losses; other Allied navies added to the toll.
They also conducted reconnaissance patrols, landed special forces and guerrilla troops and performed search and rescue tasks. The majority of the submarines involved were from the U.S. Navy, with the British Royal Navy committing the second largest number of boats and the Royal Netherlands Navy contributing smaller numbers of boats.
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 air force in the world, after the United States Air Force.
The Imperial Japanese Army was the official ground-based armed force of the Empire of Japan from 1868 to 1945. It was controlled by the Imperial Japanese Army General Staff Office and the Ministry of the Army, both of which were nominally subordinate to the Emperor of Japan as supreme commander of the army and the navy. Later an Inspectorate General of Aviation became the third agency with oversight of the army. During wartime or national emergencies, the nominal command functions of the emperor would be centralized in an Imperial General Headquarters (IGHQ), an ad-hoc body consisting of the chief and vice chief of the Army General Staff, the Minister of the Army, the chief and vice chief of the Naval General Staff, the Inspector General of Aviation, and the Inspector General of Military Training.
Special forces and special operations forces (SOF) are military units trained to conduct special operations. NATO has defined special operations as "military activities conducted by specially designated, organized, trained, and equipped forces, manned with selected personnel, using unconventional tactics, techniques, and modes of employment".
The Allied submarine campaign is one of the least-publicized feats in military history,in large part because of 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, and it appears the policy was executed without the knowledge or prior consent of the government. The London Naval Treaty, 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), made them de facto naval auxiliaries and removed the protection of the cruiser rules. This made restrictions on submarines effectively moot.
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, cultures and economies thereof, as well as the resulting changes to local and international relationships.
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.
The Treaty for the Limitation and Reduction of Naval Armament, commonly known as the London Naval Treaty, was an agreement between the United Kingdom, Japan, France, Italy and the United States, signed on 22 April 1930, which regulated submarine warfare and limited naval shipbuilding. Ratifications were exchanged in London on 27 October 1930, and the treaty went into effect on the same day. It was registered in League of Nations Treaty Series on 6 February 1931.
The U.S. had the largest and most powerful submarine force of all the Allied countries in the Pacific at the outbreak of war.[ citation needed ] Pre-war U.S. Navy doctrine—like that of all major navies—specified that 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, to which the U.S. was a signatory. The U.S. Navy built large submarines which boasted long range, a relatively fast cruising speed and a heavy armament of torpedoes. United States submarines were better suited for long patrols in the tropics than those of the other major powers due to amenities such as air conditioning (which German U-boats, for instance, lacked) and fresh water distillation units.[ citation needed ] The submarines' commanders and crewmen were considered elite and enjoyed a strong esprit. On 7 December 1941, the USN had 55 fleet- and 18 medium-sized submarines (S-boats) in the Pacific, 38 submarines elsewhere, and 73 under construction. (By war's end, the U.S. had completed 228 submarines.)
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.
Air conditioning is the process of removing heat and moisture from the interior of an occupied space, to improve the comfort of occupants. Air conditioning can be used in both domestic and commercial environments. This process is most commonly used to achieve a more comfortable interior environment, typically for humans and other animals; however, air conditioning is also used to cool/dehumidify rooms filled with heat-producing electronic devices, such as computer servers, power amplifiers, and even to display and store some delicate products, such as artwork.
While Britain stationed a force of submarines in the Far East prior to the outbreak of war, no boats 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 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 flotillas and all their submarines were withdrawn in mid-1940 to reinforce the Mediterranean Fleet.
The United Kingdom (UK), officially the United Kingdom of Great Britain and Northern Ireland, and sometimes referred to as Britain, is a sovereign country located off the north-western coast of the European mainland. The United Kingdom includes the island of Great Britain, the north-eastern part of the island of Ireland, and many smaller islands. Northern Ireland is the only part of the United Kingdom that shares a land border with another sovereign state, the Republic of Ireland. Apart from this land border, the United Kingdom is surrounded by the Atlantic Ocean, with the North Sea to the east, the English Channel to the south and the Celtic Sea to the south-west, giving it the 12th-longest coastline in the world. The Irish Sea lies between Great Britain and Ireland. With an area of 242,500 square kilometres (93,600 sq mi), the United Kingdom is the 78th-largest sovereign state in the world. It is also the 22nd-most populous country, with an estimated 66.0 million inhabitants in 2017.
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. Groups of larger warships are usually called squadrons, but similar units of non-capital ships may be called squadrons in some instances, and flotillas in others. Formations including more than one capital ships, e.g. men-of-war, battleships, and aircraft carriers, typically alongside smaller ships and support craft, are typically called fleets, each portion led by a capital ship being a squadron or task force.
The British Mediterranean Fleet also known as the Mediterranean Station was part of the Royal Navy. The Fleet was one of the most prestigious commands in the navy for the majority of its history, defending the vital sea link between the United Kingdom and the majority of the British Empire in the Eastern Hemisphere. The first Commander-in-Chief for the Mediterranean Fleet was the appointment of General at Sea Robert Blake in September 1654 the Fleet was in existence until 1967.
The Netherlands 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, most of which were obsolete.
The Netherlands, also commonly known as Holland, is a country located mainly in Northwestern Europe. The European portion of the Netherlands consists of twelve separate provinces that border Germany to the east, Belgium to the south, and the North Sea to the northwest, with maritime borders in the North Sea with Belgium, Germany and the United Kingdom. Together with three island territories in the Caribbean Sea—Bonaire, Sint Eustatius and Saba— it forms a constituent country of the Kingdom of the Netherlands. The official language is Dutch, but a secondary official language in the province of Friesland is West Frisian.
Surabaya is the capital of East Java province, and the second-largest city in Indonesia. The city has a population of over 3 million within the city proper and over 10 million in the Greater Surabaya metropolitan area, known as Gerbangkertosusila. Located on northeastern Java on the Madura Strait, it is one of the earliest port cities in Southeast Asia. According to the National Development Planning Agency, Surabaya is one of the four main central cities of Indonesia, alongside Medan, Jakarta, and Makassar.
Throughout the war, Japan was dependent on sea transport to provide adequate resources, including food, to the home islands and supply its military at garrisons across the Pacific. Before the war, Japan estimated the nation required 5,900,000 long ton s (6,000,000 t ) of shipping to maintain the domestic economy and military during a major war. At the time of the attack on Pearl Harbor Japan's shipping capacity was much greater than that, totaling 7,600,000 long tons (7,700,000 t) of shipping: the Japanese merchant fleet was capable of 6,400,000 long tons (6,500,000 t), and smaller craft were capable of an additional 1,200,000 long tons (1,200,000 t).
At the start of the war, the U.S. submarine fleet was ineffective, for multiple reasons:
Despite an awareness that shipping was vital, the Japanese military seriously underestimated the (eventual) threat from Allied submarines. This overconfidence was reinforced by the ineffectiveness of Allied submarines in the early part of the war.Anti-submarine warfare was accorded a low priority and few warships and aircraft were allocated to protecting merchant shipping. Japanese destroyers formed the bulk of convoy protection; they had impressive night fighting capabilities, but had deficiencies in sonar and radar compared to equivalents of other navies. Moreover, Japanese Navy doctrine in relation to commerce defense was very bad.
The size and effectiveness of the Allied submarine force increased greatly during the Pacific War. The U.S. increased production of modern submarines from 1942 onward. The efforts of Admiral Charles A. Lockwood were crucial for the rectification of the Mark 14's problems (which were nevertheless not resolved until September 1943).He also selected more aggressive submarine skippers. Signals intelligence broke the "maru code" in January 1943, after a gaffe by U.S. Customs pre-war had caused Japan to change it. American aircraft engaged in aerial minelaying in Operation Starvation. As a result of all of these developments, U.S. submarines inflicted devastating losses on Japanese merchant shipping in 1943 and 1944, and by January 1945 had effectively destroyed the Japanese merchant fleet.
Poor torpedoes claimed at least two U.S. submarinesout of 42 lost on patrol.
In a break with pre-war doctrine (which, like Japan's, had presumed a rush across the Pacific and a "decisive battle" between battleships),with the London Naval Treaty, and with long-standing U.S. defense of freedom of the seas, U.S. naval commanders in the Pacific were ordered by the U.S. Navy Chief of Staff to "execute unrestricted air and submarine warfare against Japan" on the afternoon of 7 December 1941, six hours after the Japanese attack. This order authorized all U.S. submarines in the Pacific to attack and sink any warship, commercial vessel, or civilian passenger ship flying the Japanese flag, without warning. Thomas C. Hart, commander in chief, U.S. Asiatic Fleet, issued the same order at 03:45 Manila time (09:15 in Hawaii, 14:45 in DC) on his own initiative (but knowing U.S. Navy Chief of Operations Harold "Betty" Stark intended to do so).
The Pacific Fleet submarine force had emerged unscathed from the attack on Pearl Harbor and USS Gudgeon departed on the fleet's first offensive war patrol on 11 December. The Asiatic Fleet's 27 submarines (including more fleet boats than at Pearl Harbor) also went into action on the first day of U.S. involvement in the war, beginning war patrols in the waters around the Philippines and Indochina. Due to inadequate prewar planning, which made no provision for defensive minelaying, nor for 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 in the Dutch East Indies (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. 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, Western Australia, 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 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, and these had little impact on Japanese forces in the area.
After the Battle of Coral Sea, the U.S. Navy detached eight submarines to finish off the damaged aircraft carrier Shōkaku, but she evaded all of them. At the Battle of Midway, although the attack on the battleship Kirishima by USS Nautilus 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 USS Enterprise's VB-6 to the Japanese task force, where the dive bombers promptly sank four fleet carriers. Overall in 1942, U.S. submarines had managed to sink the heavy cruiser Kako and the light cruiser Tenryū.
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 Taihō in the Battle of the Philippine Sea, and sank or disabled three Takao-class cruisers at the start of the Battle of Leyte Gulf. Also sunk that year were the battleship Kongō (being the only Japanese battleship lost to a submarine) and the carrier Shinano, 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 1,300 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 better suited for convoy duties, while it also did not have the industrial might to replace the losses of its heavily armed destroyers, nor of its ill-protected merchantmen.
In 1943, U.S. Congressman Andrew J. May revealed the fact that Japanese depth charges were not set deep enough to destroy U.S. submarines. Japanese anti-submarine warfare grew in effectiveness, particularly after the debut of radar in the IJN.
The British submarine force in the Far East was greatly expanded from August 1943 onward. The British Eastern Fleet was responsible for submarine operations in the Bay of Bengal, Strait of Malacca as far as Singapore, and the western coast of Sumatra 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. 40,000 long tons (41,000 t) of merchant ships, and nearly 100 small vessels.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,
The British submarine force expanded its areas of operation in the last months of the war. In late 1944, the 8th Flotilla—with 11 British and Dutch submarines—was transferred to Fremantle and operated in the Java Sea and surrounding areas under the command of the U.S 7th Fleet. The 4th Flotilla and the newly formed 2nd 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 8th Flotilla moved to Subic Bay in the Philippines and the 4th 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 HMS Trenchant torpedoed and sank the heavy cruiser Ashigara in the Bangka Strait, taking down some 1,200 Japanese army troops.
Three British submarines were sunk by the Japanese during the war: HMS Stratagem, HMS Porpoise, and HMS Stonehenge (which was mined).
Different sources provide varying figures for the size of the Japanese merchant marine and its wartime losses.
Size of the Japanese merchant fleet during World War II (all figures in tons)
|Date||Additions||Losses||Net change||End of period|
|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)
|Date||Starting tonnage||Additions||Losses||Net change||End of period|
|1942 (including 12/41)||5,975,000||111,000||725,000||−89,000||5,886,000|
|end of war||3,903,000||1,983,000|
One Japanese reference reports 15,518 civilian ships lost. 7,913,858 long tons (8,040,851 t) and 611 IJN ships lost with a total tonnage of 1,822,210 long tons (1,851,450 t).JANAC reports 2,117 Japanese merchant ships lost with a total tonnage of
In addition to taking a heavy toll on Japan's merchant shipping, a large number of troop-ships were also sunk. This resulted in the loss of thousands of Japanese troops, who were being transported to bolster Japan's already declining manpower on land in the final years of the war. Allied submarines sank an estimated 35 troopships with more than 1,000 casualties.The threat of submarine attack seriously hampered the ability of the Japanese Army to move troops.
Unfortunately Allied submarines also sank a number of hell ships, which were transporting Allied POWs and Romusha slave labourers. It is estimated that 10,800 POWs died at sea. Most of these deaths were the result of an allied submarine attack.Donald L. Miller has estimated the loss of life among POWs was twice that, asserting "approximately 21,000 Allied POWs died at sea, about 19,000 of them killed by friendly fire."
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), 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 attacks on Japanese commerce.
They also occasionally transported commandos, such as Nautilus and Argonaut landing Marine Raiders for an abortive raid on Makin Atoll.
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, who later became the 41st President of the United States).
British and Dutch submarines also landed and supplied special forces troops, rescued airmen, and shelled shore installations on nine occasions.
Britain also deployed a flotilla of midget submarines to the Far East which were used to conduct sabotage raids. The Fourteenth Flotilla, which was equipped with six XE-class submarines, 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 at Singapore.On 31 July, XE4 cut the submerged Singapore-Saigon telegraph cable near Cape St. Jacques in French Indochina and XE5 cut the Hong Kong-Saigon cable close to Lamma Island, Hong Kong. At the same time, XE1 and XE3 penetrated the Straits of Johor where they severely damaged the Japanese heavy cruiser Takao with limpet mines.
Allied actions in the Pacific are believed to have been a mitigating factor in reducing the sentence of Großadmiral Karl Dönitz following the Nuremberg Trials, 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.The official judgment of the International Military Tribunal cited the statement as part of the reason Donitz's sentence was "not assessed on the ground of his breaches of the international law of submarine warfare."
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.
U-boat is an anglicised version of the German word U-Boot[ˈuːboːt](
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. It may also be used in a non-military sense, for example when driving through remote areas. Arriving at the scene of a major emergency with a well-ordered unit and intact command structure can be another motivation.
The Battle of the Atlantic was the longest continuous military campaign in World War II, running from 1939 to the defeat of Nazi Germany in 1945, and was a major part of the Naval history of World War II. 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 height from mid-1940 through to the end of 1943.
War Plan Orange refers to a series of United States Joint Army and Navy Board war plans for dealing with a possible war with Japan during the years between the First and Second World Wars. It failed to foresee the significance of the technological changes to naval warfare including the submarine, air support and aircraft carriers, and although the Battle of Midway was important, and the US Navy did "island-hop" to regain lost territory, there was no culminating "showdown" battle as anticipated by Plan Orange.
Submarine warfare is one of the four divisions of underwater warfare, the others being anti-submarine warfare, mine warfare and mine countermeasures.
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".
Harold Rainsford Stark was an officer in the United States Navy during World War I and World War II, who served as the 8th Chief of Naval Operations from August 1, 1939 to March 26, 1942.
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.
A depot ship is an auxiliary ship used as a mobile or fixed base for submarines, destroyers, minesweepers, fast attack craft, landing craft, or other small ships with similarly limited space for maintenance equipment and crew dining, berthing and relaxation. Depot ships may be identified as tenders in American English. Depot ships may be specifically designed for their purpose or be converted from another purpose.
Joint Army–Navy Assessment Committee (JANAC) 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.
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.
The Take-Ichi sendan was a Japanese convoy of World War II. The convoy left Shanghai on 17 April 1944, carrying two infantry divisions to reinforce Japan's defensive positions in the Philippines and western New Guinea. United States Navy (USN) submarines attacked the convoy on 26 April and 6 May, sinking four transports and killing more than 4,000 soldiers. These losses caused the convoy to be diverted to Halmahera, where the surviving soldiers and their equipment were unloaded.
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.
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.
Operation Kita was conducted by the Imperial Japanese Navy (IJN) during the Pacific War in February 1945. Its purpose was to return two Ise-class hybrid battleship-aircraft carriers and four escort ships to Japan from Singapore, where they had been based since November the previous year. The movement of the Japanese force was detected by the Allies, but all attempts to attack it with submarines and aircraft failed. Nevertheless, as a result of the intensifying Allied blockade of Japan, the Ise-class battleship-carriers and their escorts were among the last IJN warships to safely reach the country from the Southwest Pacific before the end of the war.
The 2nd Special Squadron was an Imperial Japanese Navy fleet. In accordance with the Anglo-Japanese Alliance, the fleet helped defend Allied shipping in the Mediterranean theater of operations of World War I.
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