Figure 1.--Here we see an American boy standing near a torpedo is in a city park somewhere in America. I am guessing it was some time after World War I. This was a rather unusual park display and somewhat ironic. Three countries deployed major sunmarine forces in World War II: Germany, Jaoan, and the United States. Ironically the only country that waged a successful campaign was America and the U.S. Navy began the War without an effective torpedo.

"With the wartime requirement of more than 5 million tons per year, it is apparent that the health of the steel industry production was dependent on the avaiability of merchant shipping, and the fact that the supply could be cut was directly due to the operations of United States submarines."

While the German submarine campaign in the North Atlantic failed, the American submarine campaign in the Pacific proved spectacularly successful. Hampered by ineffective torpedoes in 1942, the American submarines by 1943 began to significantly affect the delivery of raw materials to Japan. The American submarines targeted the Japanese merchant marine (maru) fleet. While the big fleet carriers got the headlines. The American submarines sunk over 50 percent of all vessels destroyed during the War. The Japanese merchant marine was almost completely destroying, cutting the country's war industries off from supplies and bringing the country close to starvation by 1945. The American submarines did to Japan what the German u-boats tried to do to Britain. Surprisingly the Japanese submarine fleet had little impact on the Pacific campaign. Unlike the Americans, the Japanese began the War with the effective Type 93 Long-Lance Torpedo. The Japanese Navy never used their submarines to interdict American supply vessels. Rather they were used to target fighting ships with only limited success because of their tactical deployment. The Japanese used theor submarines as scouts and to targer warships. As the American offensive moved toward the Home Islands, the Japanese used their submarines to supply bypassed island garisons, some of which were near starvation. They were also used to supply bypassed islasnd bases where garrisons were close to starvation. They also managed to get some secret German military technology to Japan late in the war (1944).

Overview

While the German submarine campaign in the North Atlantic failed, the American submarine campaign in the Pacific proved spectacularly successful. The Japanese which entered the War with a substantial submarine force armed with the world's most effective torpedo did not play an important part in the War.

Japanese Vulnerability

Japan was a country that ws largely immune from forteign invsioin even defeating a vast Mongol invasion fleet. This changed in the 20th century with indudtrialization. The increased popultion a a result of idustrialization meant that Japan with its limited agricultural potetial no longr was able to grow the food needed to feed its population. Jopan not only needed to import food, but with its very limited possession of raw materaials meant that Japan had to import therawmaterails needed by its factories. Japan hacoal, but that was about it. And the gowing improtance of oil in the 20th centry made matters worse. Jaan had no maninful oil resource.

Japanese Mercant Marine: The Marus

Japan's industrialization required not only rail transport, but maritime transport as well. Japan needed to import raw materials and export its manufactured goods. For this because of its island geography, Japan needed to build a sea-going maritime (maru) fleet. This was some that had to be built up from scratch. The Shogun had cut off Japan from the world economy. Only a few Dutch ships were allowed to call at a single port. The turning point was Commodore Perry Black Ships (1853). The Japanese merchant marine transformed from a primarily coastal and regional fleet to a global force. It began to expand to support Japan's industrial development (late-19th century). Just before the War, a naval historian wrote, "The rise in power and prestige of the Japanese merchant fleet since the advent of the iron ship is a maritime exploit of unparalleled proportions. A single generation ago Japan’s merchant marine consisted of 20 sailing vessels for every steamship and the operation of the fleet was confined principally to the China service and the coastal trade. Today her shipping companies operate vessels on regular runs over the principal sea lanes of the world. Her tramps dot every ocean and compete for cargo in every port of the globe." 【 McCormick 】 Japan lunched the First Sino-Japanese War broke out in 1894 and it was at this time that the Japanese shipping industry made great strides for the fir... The Japanese merchant marine fleet totaled 6.3 million gross tons or about 8 per cent of the world's tonnage when World War II broke out in Europe (1939). It ranked third only after Britain and the United States. This was adequate for an important industrial nation. The problem for Japan was that in war time the need for maritime transport escalates, especially a naval war fought over the vast distances of the Pacific Ocean. With Japanese attack on at Pearl Harbor the country's merchant marine was converted for war-time service, serving as troop transports, delivering arms and and ammunition and other supplies to wide-spread Pacific garrisons. Japan went into a construction frenzy to expand the maru fleet. The Japanese tried to make available Maru tonnage do by ordering garrisons to become self sufficient in food supplies. The result was that large numbers of Japanese military personnel as well as the civilian population in the occupied territories starved. During the Pacific War, the United Sates destroyed some 8 million gross tons of merchant ship tonnage. This was more than Japan began the war with because if the ships built during the War. were lost, including the vessels built during the war. This did not occur in a slow drip by drip process. Ship losses were very limited in 1942 and most of 1943. The Japanese dominated the seas in 1942 and still had a significant presence during 1943. The United States launched unrestricted submarine warfare within hours of Pearl Harbor. The problem was that the Submarine Service was not trained for this and too many of the torpedoes were defective. These problems were not addressed for over a year and half. Once this was addressed, the sin kings escalated and in about a year the maru fleet was largely destroyed. This cut the war factories of the Home islands off from needed raw materials. Japan began the War with a much smaller industrial base than America now had factories cut off from raw materials. And this was before the American strategic bombing campaign had kicked in.

Japanese Convoy System

The Imperial Japanese Navy went to war with a peace time merchant marine (Maru) fleet. There appears to have been limited realization that far more cargo vessels were needed for war than for peace time commerce. We see some Maru construction in the years leading up to th War. The Japanese Marus not only had to do the normal pre-war functions but to support military operations in distant battle fields and to supply the military garrisons set up on countless Pacific islands. Marus wee not armed and no convoy system was contemplated. The Imperial Navy assumed that they could control the seas in the Western Pacific and the Marus would be untouched. And that there would not be a long war. er initial victories like Tsushima (1905), the Americans would accept defeat and accept Japanese control of the Western Pacific. The Japanese were not interested in using their submarines to wage a commerce campaign. They assumed that the Americans would either do the same or did not have the capability to do within the waters of the Japanese Empire. In the first2 years of the Pacific War only 25 Imperial Navy vessels wee regularly assigned to escort duties. This worked because the American Submarine Service was not trained for commerce raiding and the American torpedoes were defective. Of course submarines were not the only way of interdicting Japanese Marus, but they were by far the most important. These problems were rectified until late-1943. As a result, the Japanese were forced to begin convoying. It proved to be too little and too late. By this time the Japanese had lost large numbers of the destroyers needed for convoy escorting. As the destroyers were not available, the IJN distributed some 40 subchasers to convoy escorting (March 1944). These small vessels were no suitable for high-seas escorting. The subchasers were assigned to naval bases for local defenses. Other vessels assigned to escort duties were older vessels not seen a valuable for fleet operations. Most of the Marus sailed unescorted. The Japanese system was to make naval bases responsible for the Marus passing through its area of responsibility.

Allied Submarine Campaign

American submarine campaign

The Ameriican submarine campaign was hampered by poor strategic and tactical concepts and ineffective torpedoes in 1942. The American submarines by 1943, however, began to significantly affect the delivery of raw materials to Japan. The American submarines targeted the Japanese merchant marine (maru) fleet. While the big fleet carriers got the headlines. The American submarines sunk over 50 percent of all vessels destroyed during the War. The Japanese merchant marine was almost completely destroying, cutting the country's war industries off from supplies and bringing the country close to starvation by 1945. The American submarines did to Japan what the German u-boats tried to do to Britain. Surprisingly the Japanese submarine fleet had little impact on the Pacific campaign. Unlike the Americans, the Japanese began the War with the effective Type 93 Long-Lance Torpedo. The Japanese Navy never used their submarines to interdict American supply vessels. Rather they were used to target fighting ships with only limited success because of their tactical deployment. The Japanese used theor submarines as scouts and to targer warships. As the American offensive moved toward the Home Islands, the Japanese used their submarines to supply bypassed island garisons, some of which were near starvation. They were also used to supply bypassed islasnd bases where garrisons were close to starvation. They also managed to get some secret German military technology to Japan late in the war (1944).

British submarine campaign

The British were of course primarily focused on the Atlantic when Germany and the Soviets launched Worlod War II (1939). There was only limited uses for submarines in yhe Bsttle of the Alantic. Few German merchantmen continued operating in the Atlantic and the Germans did not have a large enough navy to conduct extensive fleet oprations. This chjanged when Italy entered the War and declared war on Brirain and France. Here British submarines would play an imprtant role in interdicting supplies snd reinforcement to first Italian snd then German forces operating in North Africa. Aided by Ultra, they were very successful, essentially obliteratin the Italian merchasnt fkleet. The Mediterranean focus changed with the destruction of Axis forces (and the surrebder in Tunisia (May 1943). This meant that strong submarine forces were no longer needed. And many submarines began to be shifted to the Indian and Pacific Ocean (August 1943). We believe that they at fursdt they mostly opetasted out of Ceylon (Sri Lanka). Royal Navy submarine were not hsmpered by faulty torpedoes like the Americans. We are nmot sure tob what extent they had the commsnd problems of the Americans. (Pre-War American sunmarine dioctrine emphasized caution as opposed to gthe needed caution.) The British area of operation was primarily in the Indian Ocean to support CBI operatiions in India abd Burma. The Royal Navy Eastern Fleet submarines concentrated on the Bay of Bengal, Strait of Malacca, asnd the western coast of Sumatra. This was not where the Japanese maru (merchant) fleet was active. The whole purpose of launching the Pacific War was to obtain the resources of the Southern Resource Zoner, especilly oil. Thus the marus were mostly found in the Pacifuic sealanes from the Dutch East Indfies north to the Home Islands. There was nuch less traffic west to Burma. Thus the British submarines primarily encountered small craft like junks sailing inshore waters. 【Mars, p.216.】 The Britisdh submarines were deployed uin the Tndin Ocean for reconnaissance, interdict Japanese supplies, and attack Germsn U-boats operating from Penang, Thailand. The Royal Navy continued expasnding its Eastern Fleet's submarine submarine forced (1944). They had some limited successes, including a cruiser, 3 submarines, 6 small naval vessels, 41,000 ) of merchant ships, and nearly 100 small vessels. 【McCartney, pp.40–42.】 This of course was a small fraction of the American tally. After the Battle of Leyte Gulf (October 1944), the Royal Navy began expanding operations into the Pacific. The American focus also shifted, bringing the war to the area around the Home Islands. The Royal Navy's 8th Flotilla which included Dutch submarines was transferred to Fremantle and operated in the Java Sea and surrounding areas under the overall command of the American 7th Fleet. The Royal Navy Flotilla and the newly formed 2nd Flotilla remained in Ceylon. The Royal Navy would achive control of the Strait of Malacca, preventing any supplies from reaching the Japanese forces in Burma by ship. They encountered few Japanese marus and the Btritish submarines mainly operated against small coastal boars which were sunkl by using their deck guns. he American submasriners were doing the same. The 8th Flotilla moved to Subic Bay asfter thev liberation of the Philippines (Aprril 1945). This putv themn in the oposition to joinn the Americans in operastions around the Hime Islands. The 4th Flotilla replaced then at Fremantle for iperastions in DEI waters , islands still herld by the Jaoanese. The Royal Navy Eastern submarine force at this time included 38 British and Dutch submarines and an additional five boats in transit from Europe. HMS Trenchant torpedoed and sank the heavy cruiser Ashigara in the Bangka Strait in the Java Sea. Three British submarines were sunk by the Japanese during the war: HMS Stratagem, HMS Porpoise, and HMS Stonehenge (mined). 【McCartney (2006), pp.42–43.】 This suggests to us that British submarub=ne commanders were less aggressive than American commandders. The U.S. Navy Pacific Fleet submainers suffered the highest casualty rate of all the American armed forces--losing 20 percent of submariners. a total of 50 in operations against the Japanese.

Dutch Submarine campaign

At the time of World WarII, the Dutch fleet was primrily in the Pacific, protectig the Dutch WascIndies (modern Indonesia). As a result, when the Gemans invaded only asmall prt f the fleet was destroyed or captured and some of the vesselsin Europe escaped to Britain.

Axis Submarine Campaign

German submarine campaign

The Germans tried to convince the Japanese that they shouild use theior substantial submarne force for a comerce war. The vast Pacific Ocean ioffeed a range of opportunities for the Japanes, but they were no ubterested. Japanese naval doctrie put a great emphassis on pn fleet action and this meant attackig eneny war ships not merchant en. There was no glory in sinking a merchantman. The Germans deployed a few U-boats in the Indian Ocea, They were based on Penany. Te Japanee were suspicious of the Germaans and there was little real cooperation. ee

Japanese Submarine Campaign

The Japanese Navy got its first submarines from the United States, buying them from the Electric Boat Company in the early 20th century. More sophisticated submarines were obtained as part of the World War I peace settlement. The Allies gave thge Japanese a number of German U-boats. After the War, the Japanese Navy began to focus on the American Navy as its most likely future opponent. The Japanese began building an advanced sibmarine, the I-class submarines. This submarine reflected the empire that Japan began to conceive in Southeast Asia and the Pacific. The I-boats were very large submarines, reflecting the vast distances involved in Pacific operations. The I-class were 350 ft long and had rangds of 20,000 miles, more than twice that of 7,000-8,000 mile range of the German U-boats. The Japanese had smaller subs for coastal patrol, but the backbone of the fleet was the I-class boats. Surprisingly the sunstantial Japanese submarine fleet had little impact on the Pacific campaign. Unlike the Americans, the Japanese began the War with the effective Type 93 Long-Lance Torpedo. The Japanese Navy never used their submarines to interdict American supply vessels. Rather they were used to target fighting ships with only limited success because of their tactical deployment. The Japanese used their submarines as scouts and to targer warships. As the American offensive moved toward the Home Islands, the Japanese used their submarines to supply bypassed island garisons, some of which were near starvation. They were also used to supply bypassed islasnd bases where garrisons were close to starvation. They also managed to get some secret German military technology to Japan late in the war (1944). The Japanese developed especially large sunmarines that could carry a few planes. They were planning an attack on the Panama Canal until the sumarines were redeployed to defend Okinawa (1945).

Sources

McCartney, Innes. British Submarines 1939–45 (Oxford: Ospery Publishing: 2006).

Mars, Alastair. British Submarines at War 1939–1945 (London: William Kimber, 1971).

Parish, Thomas. The Submarine: A History (Viking, 2004), 576p.

Created: 5:51 AM 6/21/2004
Last updated: 11:08 PM 5/3/2025