World War II: Japan and Oil (1939-45)

Figure 1.--Japan was almost completely dependent on imported oil for its economy and military. And most of those imports came from America. Worst still for the Japanese, the American Philippine Islands stood between the Home Islands and the Southern Resource Zone which Japan coveted. And if all of that was not bad enough, if Japan went to war it would need much more oil than peace time demand.

Modern war requires oil. All three Axis countries had a significant problem. They were not self-sufficent in petroleum. Each of the Axis countries attempted to resolve this limitation to varying degrees of success. Japan would require huge quanities of oil of it planned to wage a naval war in the vast streaches of the Pacific. Japan had to import almost all of its oil in peacetime and war would significantly increase tghe quantities required. Japan was a densly populated, resource poor country. Expansion into Korea and Manchuria (Manchuko) managed to acquire many needed resources. The most critical resource that Japan lacked was oil. And to make matters worse, the United States was the major world producer of oil. America was also Japan's principal supplier--the same country the United States would have to fight if it was to seize an empire in the resource-rich South Pacific--especially the DEI which had developed important oil fields. The United States attempted to disuade Japan from waging aggressibe war in China. The United States began a series of trade restrictions until it became clear with Japan's move into southern Indochina that Japan was preparing to launch a major aggressive war in the Pacific. America responded with an oil embargo. Tyhis action made war inevitable. It only became a question of when and where Japn would strike. Japan had oil stockpiles that could supply its normal needs for 2 years, but only about 1 year if Japan went to war because of the huge increased requirements to fight a naval war. This set in motion a time table. Japan had either to decide to cease aggression in China or go to war before it ran out of oil.

Japanese Oil Production

Japan was a densly populated, resource poor country. The most critical resource that Japan lacked was oil. Japan did have some limited sources of oil. Japan produced about 2.7 million barrels of oil domestically. The domestic wells were located at Akita, Niigata and Nutsu. This was about 0.1 percent of world production (1941). This was approximately comparable to a single day of American oil production. Expansion into Korea and Manchuria (Manchuko) managed to acquire many needed resources. Manchukuo fields provided another 1.0 million barrels. They obtained another 1.0 million tons from fields in Formosa (Taiwan). Japan also had a small synthetic petroleum industry.

Japanese Oil Requirements

And with an industrial economy and a large navy and merchant marine, Japan required large quantities of oil. The ongoing war in China also required large quantities of oil.

Japanese Oil Imports

Japan was almost totally dependant on imported oil. Japan imported about 90 percent of its oil. To make matters worse for Japan, the United States was the major world producer of oil. America was also Japan's principal supplier--the same country the United States would have to fight if it was to seize an empire in the resource-rich South Pacific. Japan imported 1.0 million barrels from Soviet Sakhalin. Japan also imported oil from the DEI amd Mexico, but the United States was the primary source. Japan's major source of oil was the United States. Before the invasion of China, Japan had been purchasing 80 percent of its oil in the United States (1937). The United States through its moral persuasion policy had suceeded in convincing American ship owners to reduce shipments to Japan without any formal action. Thus on the brink of war the Japanese were only obtaining 60 percent of their oil in America (1941).

American Diplomacy

The United States attempted to disuade Japan from waging aggressive war in China. This proved ineffectual as the Japanese military steadily expanded it role in the Government. And the military even more than the civilians were convinced that Japan both needed and deserved a colonial empire. They saw that as not only appropriate for a great power, but necessary for the Japnese economy. Their major goal was China. Japan was blunted by the Red Army in efforts to Strike North (August 1939). Siberia had vast resources, but at the time, oil was not one of them. The Strike South Faction gradually gained power and here the oil and other resources of Southeast Asia beackoned. In the face of these domestic political developments, American diplomacy proved ineffectual. There was essentially nothing the United States could have dine short of recognizing the Japanese cinquest of China. And of course there is no assurance that Japanese aggression would have stopped there.


The war in Europe opened new opportunities for the Japanese. The fall of France to the Germans rendered the French incapable of defending their colonial possessions. Hitler in the Franco-German Armistice (June 1940) allowed the new French Governmeny in occupied Vichy to retain control of its colonies. This meant that the Japanese could move against Indochina. Indochina was important for a variety of reasons. Indochina had some resources, but it was geography that primarily attracted the Japanese interest. Possession of northern Indochina closed one of the last routes through which the Allies, primarily America, could aid China. Possession of southern Indochina put the Japanese within striking distance of the oil-rich DEI and Malya through which they could attack Singapore. The Japanese first moved against northern Indochina. Even before the Frwnch surrendered to the Germans, the Japanese French Ambassador in Tokyo with a series of demands (June 19). Tokyo demanded that France immediately cease shipment of all war materiel to China and to amnit a Japanese Control Commission to regulate the border with China. Japanese troops massed on the Chinese border with Indochina and Imperial Navy ships sailed into the Gulf of Tonkin to demonstrate that these were no longr requests. The Japanese Government gave the French 48 hours to comply. The Japanese at the same time demanded that the British cease deliveries of war material to China over the Burma Road. An agreement was finally reached with the new Vichy Government which did not have the capability of resisting the Japanese (August 30). This allowed the Japanese to move military forces into the northern area of French Indochina (1940). A major goal of the Japanese was to cut off the flow of military supplies to China. The Japanese not only achieved that objective, but now could uae French airfiekds to bomb Chinese targets.

American Response

Shortly after the Japanese began to move into French Indochina, American code breakers broke into the Japanese diplomatic Purple code (September 1940). The results confirmed what American diplomats had long believed, that Japan despite public protestations to the contrary, was preparing for war. The United States in response began a series of trade restrictions to disuade Japan from continuing the war in China and further aggressive steps in Southeast Asia, The first step was the Export Control Act (July 1940). Japan responded with the Tripartite Pact (September 27, 1940) joining with the Germans and Italians, but not entering War. The goal was to deflect American pressure. The result was to harden American policy. The United States for some time cheld back from the ultimate embargo--oil. The Magic decrypts made Japanese intentions clear as did their move into southern Indichina. The United States thus well before Pearl Harbor knew that Japan was preparing an aggressive war in the Pacific.

American Oil Embargo (July 1941)

With the Japanese occupation of northern Indochina and the revealing Purple intercepts indicating that the Japanese were untent on seizing the Southern Resource Zone, the Rosevelt Administratin began debating how to respond. The Cabinent was divided. Secretaries Morgenthau, Stimson, and Ickes argued for a real embargo that would really affect Japan--namely an oil embargo. The British wee pushing for such an embargo. State Secretary Hull argued against an oil embargo. He was supported by the Navy Department which would have to fight awar in the Pacific. They argued that an oil embargo were tantamount to declaring war. They were right, but did not understand that the Japanese had were moving toward war even without such an embrgo. President Roosevely, understanding tha an oil embargo meant war, vacillated, not yet ready to make such a momentous decesion. Chief of Naval Operations, Admiral Harold Stark dispatched a formal memorandum to President Roosevelt clearly stating that an oil embargo meant war (July 24). That same day in the afternoon, Ambssador Nomura, President Roosevelt, Admiral Stark, and Under-Secretary of Stte Welles met in the White House. Roosevelt not yet aware that the Japanese had forced Vichy to consent to the occupation of southern Indochina, suggested to Nomura that an adiplomatic accomodation could be found on the basis of the neutralization of Indochina. He emphasized the key was that no Japanese occupation must take place. Roosevelt spoke openly to Nomura who he respecte. He explained that the United States had abstained from imposing an oil embargo because he had no desire to give Japan an excuse for seizing the oil fields of the oil-rich Dutch East Indies. He also explained that he could not justify continued oil deliveries to Japan if Japan was to continue agression. He said American public opinion would not accept this, especially with gasoline rationing. When Ambassador Nomura returned to the Japanese Embassy, he cabeled Tokyo expressing his opinion that American embargoes were eminent if the Japanese didn't accept the President's proposal on the neutralization of Indochina. The Japanese Government never responded. The Japanese move into southern Indochina finally convinced America that stronger action was needed. Southern Indochina brought the Japanese within striking range of the American Phillipine Islands, British Malaya and Singapore, and the DEI. The final American action was President Roosevelt issuing Executive Order 8832 (July 26, 1941). This froze Japanese funds in America. [Anderson] Britain and the Dutch Government in Exile followed suit. This essentially meant a total trade embargo. Not only could Japan not by oil and petroleum products (aviation fuel) in the United States, but it now did not havec thecforeign exchange reserves to buy oil from other sources, even the DEI. To make the the American position crystal clear, President Roosevelt issued Executive Order ?????? (August 1). This order specifically banned the export of petroleum products to Japan. Britain, the Dutch, New Zealand, and the Philippines followed suit.

Clock Running

Japan had to import most of its oil in peace time and from the United States. War would require vastly increased oil supplies. Waging naval war in the vast streaches of the Pacific would mean huge increases in oik consumption. Japan had oil stockpiles that could supply its normal needs for 2 years, but only about 1 year if Japan went to war because of the huge increased requirements to fight a naval war. The merican oil embargo set in motion a time table. Japan with the clock ticking had either to decide to cease aggression in China or go to war before it ran out of oil. The oil embargo and assets-freezing order according to one historian “made war with Japan inevitable….” [Morison] He explains that “a general impoverishment” of the Japanese economy was threatened with insufficient oil for “normal domestic consumption, let along naval operations.” Japan of course had the option of making peace. But the miklitarists who invaded China would not be turned from conquering China by mere economic sanctions. Rather their answer was more wore, seizing the resource rich Soutghern Resource Zone (SRZ).

Japanese Offensive (December 1941-June 1942)

As Japanese naval commander Yamamoto struck first at Pearl Harbor (December 1941). Spearheaded by the powerful First Air Fleet, Japan in 6 months after Pearl swept ower Southeast Asian and the central Pacific with largely ineffective Allied opposition. The American Pacific Fleet was largely imobilized, although the American carroers, Yamaoto's primry target, had not been at Pearl. The British position in the Far East was based on Singapore. The fall of Singapore (February 1942) shockjed the world and opened the way for the rapid seizure of Burma and the Dutch East Indies. Japan also attacked the American forces in the Philippines, destroying most of the Air Corps planes on the ground, even though MacArthur had reports of the attack on Pearl Harbor several hours before the Japanese struck his air fields. The American in the Philippines held out for several months before running out of supplies and surrendering (April 1942). America soon learned of Japanese attrocities during the Battan Death, fueling American hatred of the Japanese. After naval victories, Japanese paratroopers successfully seized the Dutch oil field lsrgely in tact. Japan then invaded New Guinea and the Solomons in preparation for an eventual assault on Australia.

Dutch East Indies

The Dutch interest in the Indies was initially spices. With the Industrial Revolution in Europe, demand rose for a range of natural resources. And the DEI was rich in many important industrial resources. The single most important resource was oil. Most of the oil came from from Sumatra. The DEI oil was most abundant and among the sweetest crude oil produced anywhere in the world. The Dutch Indonesian oil fields were some of oldest in the world. Commercial fields were discovered in northern Sumatra (1883). The Koninklijke Nederlandsche Maatschappij tot Exploitatie van Petroleum-bronnen in Nederlandsch Indië (Royal Dutch Company for Exploration of Petroleum sources in the Netherlands Indies) ws founded (1890). The Shell Transport and Trading Company was a British company that had began drilling in Kalimantan (1891). The two companies merged to form Royal Dutch Shell (1907). Royal Dutch Shell became a major international oil giant. Initially they dominated oil exploration in the British and Dutch Malay-Indonesian colonies for three decades. Royal Dutch Shell was soon operating concessions in Sumatra, Java, and Kalimantan (Borneo). Royal Dutch's output from the DEI came to represent about 4 percent of total world production. What was to become Indonesia's most important oil fields (Duri and Minas) in central Sumatr, were discovered just prior to World War II by Caltex (a joint venture between the American companies Chevron and Texaco). Production did not, however, figure in World war II. By the time of World War II, the annual output of 65 million barrels annually was more than enough to make Japan self-sufficent and fuel not only Japanese industry, but all of the increased demands that would be rquired for a naval war in the Pacfic. The DEI did not produce crude oil. The Dutch at a cost od 150 million gilders built a huge refinery at Balik Papan in eastern Borneo (1920s). Oil was, however, not the only resource. The DEI ranked only behind British Malaya in tin production. Production totaled 44,563 tons (1940). The Dutch also mined bauxite and coal in the DEI. ubber, copra, nickel, timber, quinine, and important foodstuffs such as sugar, rice, tea, and coffee.

Oil Usage

DEI Oil Production

American Submarine Campaign (1942-45)

The American submarine campaign was hampered by 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).

Oil and Fleet Deployment

Oil scarcities affected the deployment of the Imperial Fleet. The Japanese inability to being the Dutch East Indies refineries on line as quickly as planned, meant that oil in anticipated quantities did not materialize. This compounded the situation created by the Midway operation. Admiral Yamnamoto's Midway operation involved virtually every major ship in the Fleet. It used huge quantities of oil. As a result in the subsequent naval campaigns, the availability of fuel and the potential fuel usage had to be considered. Japan extensively used in cruiser force in the Solomon's campaign, but only deployed its battleships sparingly (August-November 1942). This was at a time when the American Navy had very few battleships available as a result of the Pearl Harbor attack. The availability of fuel also affected other major naval operations, especially the Battle for Leyte Gulf (October 1944). By this time the American submarine campaign had significabntly degraded the Japnese tanker fleet. The convuluted, complex Japanese battle plan was in part dictated by fuel shortahes.

Pilot Training

Japan began World War II with both superior aircraft types and an elite corps of about 400 carrier pilots. Japan's war plan called for a short war with the United States in which the the American Pacific Fleet, especially the carriers, was quickly destroyed early in the War, When the Pearl Harbor attack failed to achieve this goal, the Japanese carrier pilot force was gradually attrited, especially the all in important squadron leaders. The Japanese, unlike the Americans, did nor return especially skilled pilots to flight school to serve as instructors. Thus once lost, their skills and experience were tottaly lost to the Japanese. The United States even before Pearl Harbor had greatly expanded pilot training programs. The Japanese did also, byrt not to the extent of the Americans. The major problem they faced was the shortahe of aviation fuel. The only way to gin experience as for a plot to prticipate in extended in flight training ptograms. And this required large quantities of aviation fuel. Thus after the Ciral Sea, Midway, and the Sollomons, most of Japan's carrier pilots had been lost. This lead to the Japanese disaster in the Philippine Sea (June 1944). It proved to be the last of the great carrier battles of the War. The situation at the beginning of the War was reversed. The Americans had a greatly imroved fighter, the Hellcat, and it was the Americans who were well trained and experienced. The battle as a result, is commonly referred to as the Great Marianas Turkey Shoot.

American Bombing of Japanese Refineries

Strategic bombing was a new innovation to warfare in World War II. Air staffs had not yet worked out how to conduct such a campaign and what assetts should be targetted. The United States learned a great deal as part of the strategic bombing campaign against Germany. The seizure of the Marianas (July 1944) brought the Home Islands within the range of the new B-29 Superforts. It took some time, however, to extend the runways and establish the air groups in the Marianaa. The American Strategic Intelligence Section of the Air Staff reached the conclusion that the Japanese petroleum industry should be targeted. The Joint Chiefs of Staff believed that destroying Japanese refineries cut off fuel to the Japanese military, especially the navy navy and air force which could shorten the war. Gen. Carl A. Spaatz, commander of the U.S. Strategic Forces in Europe had noted how the destruction of the German oil industry had shortened the war in Europe. When he assumed command of the U.S. Army Strategic Forces in the Pacific, Spaatz supported the plans being drawn up to destroy the Japanese petroleum industry. Maj. Gen. Curtis E. LeMay, commander of the 20th Air Force, and Brig. Gen. Barney Giles, the deputy commander also supported the effort. The campaign, however, did not begin until rather late in the War. The assignment was given to the 315th Bomb Wing, 20th Air Force. The targets were the oil refineries and the oil storage facilities. The 315th Bomb Wing conducted 15 bombing missions against Japanese oil facilities abd succeeded in causing significant damage (June 26-August 14, 1945). The U.S. Air Force by this poit in the War was able toi hit targets with considerable accuracy. Unlike the campaign in Europe. The Japanese air defenses wee unable to significantly challenge the American bombers. General LeMay wrote to the Wing Commander, Gen. Frank Armstrong, concerning the attack on the Maruzen Oil Refinery at Shimotsu,"you achieved ninety-five percent destruction, establishing the ability of your crews with the APQ-7 to hit and destroy precision targets, operating at night. This performance is the most successful radar bombing of the Command to date." The United States Strategic Bombing Survey (USSBS), concluded that because the bombing campig against the Japanese oil industry did not begin until May 1945, the naval blockade of Japan had largely cut off oil imports leaving the refineries very little crude oil to refine. [Horowitz]


Horowitz, Manny. "Were There Strategic Oil Targets in Japan in 1945?" Air Power History Vol. 51, 2004.

Morison, Samuel Eliot. U. S. Naval Operations in World War Vol. III The Rising Sun in the Pacific.


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Created: 7:21 PM 10/17/2008
Last updated: 4:36 PM 8/30/2012