Photograph of oil wells off Santa Barbara

AAAS. Via Wikipedia Commons

From the Japanese perspective, the Pacific War was fought largely over oil. When Japan occupied southern French Indochina in July of 1941, putting her forces within striking distance of Malaya and the Netherlands East Indies, the United States, Britain, and the Netherlands responded with an oil embargo. This threatened to strangle the economy of Japan, which imported 90% of its oil (domestic production being limited to small fields at Niigata and Akita.) Japan responded with devastating attacks on Pearl Harbor and Singapore, and then seized the rich oil fields of the Netherlands East Indies and Borneo in a swift and brilliant campaign. These fields produced 65 million barrels of oil in 1940, a rate which should have been more than adequate for Japan’s import needs.

Oil was vital for the kind of naval war fought in the Pacific. It provided fuel for ships and aircraft, as well as petrochemicals. The Allies would have been in serious trouble for lack of rubber if they had not succeeded in developing processes for making synthetic rubber from oil. The United States, unlike Japan, was a major producer of oil (1.35 billion barrels a year in 1940, 63% of world production), and major fields were located in California where they were ideally situated for supplying the Navy’s needs. Additional reserves were located at Venezuela and Aruba, and the British Far East Fleet was able to draw upon supplies in the Middle East. There were also fields in Burma and northeastern India.

California produced about 15% of U.S. oil, some 203 million barrels per year, but actual pumping capacity in 1941 was 1.37 billion barrels per year. Refinery capacity was about 296 million barrels per year. The Los Angeles basin tended to produce medium to heavy crude oil suitable for refining into fuel oil for ships, while fields in the San Joaquin Valley tended to produce lighter crude oil rich in gasoline. Because there was no pipeline connection from California to the eastern United States in 1941, and transport by rail or by tanker through the Panama Canal was uneconomical, California production was consumed almost entirely around the Pacific Rim. With the outbreak of war, this vast petroleum production capacity ensured that the availability of fuel for the Allies in the Pacific would initially be limited only by tanker capacity. With construction of almost 500 T-2 standard tankers alone, the U.S. Navy was able to carry out almost continuous high-speed operations in the western Pacific by the end of the war. Total fuel oil issue in the Pacific was 17 million barrels in 1942 and 28 million  barrels in 1943, the latter almost twice the total commercial exports of petroleum products from the United States in 1941. By 1944, consumption had become so great that even the California production was inadequate, and oil began to be brought in from South America and the eastern United States.

Crude oil cost about $1.20 a barrel in the United States in 1942, and the price was held steady through the war by rationing. Bulk diesel oil cost about $10 a ton.

The United States was fortunate that the wartime relationship between the oil industry and the government was led by Harold Ickes and his talented deputy, Ralph Davies. The battle between government and the oil industry had been almost as brutal as the battles within the industry during the Great Depression, but Ickes and Davies turned this into one of the smoothest working relationships between industry and government of the wartime administration. It did not hurt that there was considerable excess production capacity that could rapidly meet the increased wartime demand. Further gains were realized with new technologies, such as fluid catalytic cracking, which greatly increased the light fraction yields (such as gasoline) from crude oil. Hydroforming likewise greatly increased the potential yield of both high-octane gasoline and toluene. By 1943, Jersey Standard's Baytown Ordnance Works in Texas was producing nearly 70 million gallons of toluene per year through hydroforming.

The Japanese Navy was well aware of the vulnerability of its fuel supply, and it had been stockpiling oil since shortly after the First World War. So great was the perceived need that, from 1925 through 1930, part of the appropriations for naval construction were secretly diverted to oil purchases, a fact the Navy concealed from its own government. The Navy also succeeded in pressuring the government to enact the Petroleum Industry Law in 1934, which required civilian oil companies to build up a reserve equal to half their annual imports. This was ostensibly to ensure that there would be a sufficient wartime supply of oil for civilian use without dipping into Navy stocks. After 1937, the Navy began a crash program to stockpile high-octane gasoline and isooctane as well.

By 13 March 1941, the Japanese had managed to stockpile about 42.7 million barrels of oil, primarily from California and Tarakan. This was stored in some 7000 oil storage tanks, also purchased from the United States. Navy petroleum product reserves on 1 December 1941 were 1,435,000 tons of crude oil; 3,634,000 tons of of bunker fuel; 473,000 tons of aviation gasoline; 27,000 tons of isooctane; 6400 tons of aircraft lubricants; 13,600 tons of ordinary lubricants; and 921,000 tons of petroleum derivatives already loaded on ships or distributed to overseas bases. This was thought to be sufficient for the first year of war, but consumption greatly exceeded prewar projections. The Army estimated it would require 5.7 million barrels of oil per year while Navy requirements were estimated at 17.6 million barrels per year and civilian requirements at 12.6 million barrels per year. This proved to be a considerable underestimate in the first two years of the war. 

Japanese oil inventories in thousands of barrels

Fiscal Year
Crude Petroleum
Refined Products
Starting Inventories


1945 (first half)

After Cohen (1949)

Willmott (1982) points out that the Japanese estimates assumed a single great fleet engagement in keeping with Decisive Battle Doctrine, rather than the long war of attrition and nearly continuous operations that actually took place.

The Japanese badly mismanaged their limited resources of oil. They took the logical step of trying to establish a synthetic oil industry based on their sizable supplies of coal, but this effort failed because of a lack of technical expertise and shortages of alloying and catalytic metals for the synthetic oil plants. The Japanese also suffered a serious loss when an American submarine chanced upon and sank a transport carrying equipment and expert personnel to the southern oil fields. However, demolition of the oil fields of the Netherlands East Indies was carried out rather poorly and production rebounded quickly. The real problem was getting the oil to Japan. The Japanese tanker fleet was never adequate, and insufficient priority was given to building more tankers. Hence much of the production from Southeast Asia never made it to Japan. Although production in Japanese-controlled areas peaked at almost four million barrels a month in 1943, imports to Japan never exceeded about 1.4 million barrels a month. In the last two years of the war, the Japanese Fleet lost its advantage of interior lines of communication because of the necessity of basing much of the fleet near its fuel sources, at Singapore or Tawi Tawi.

Japanese tanker tonnage

January 1942
July 1942
January 1943
July 1943
January 1944
July 1944
January 1945
July 1945

After Parillo (1993)

Once Allied forces were established in the Philippines and on Okinawa, Japan was cut off from the oil fields of southeast Asia. The last tanker from southeast Asia reached Japan in March 1945. So desperate was the need for oil that millions of civilians, including whole classes of schoolchildren, were assigned to dig up pine roots. These could be distilled to produce a low-quality oil. About 37,000 distillation units were improvised to yield 70,000 barrels of pine oil, from which just 3,000 barrels of aviation fuel were refined. The fuel was so contaminated with impurities that American jeeps that used the fuel during the occupation quickly suffered engine failure.

China suffered even more severe liquid fuel shortages than Japan. There was only one producing field in China, at Yumen, which produced only 50,000 tons per year. This was supplemented by mobilizing 82% of alcohol production capacity in free China for motor fuel, along with extraction of gasoline from the tung oil produced by tung trees in western China. Production of gasoline from tung oil and other vegetable oils peaked at 642,000 gallons in 1943.

Oil measure, storage, and transport

Oil is normally measured by volume in barrels with one barrel equaling 42 gallons or 159 liters. However, warship designs often specified their bunkerage by weight in metric tons, since this was used to calculate standard displacement. The conversion depends on temperature and grade of oil, but for Navy Special Fuel Oil (with a specific gravity of about 0.96) a metric ton was approximately 6.55 barrels, while for light crude oil with a specific gravity of 0.83 a metric ton was about 7.58 barrels.

Oil was typically stored in cylindrical steel tanks with a light conical weather roof and a floating top. The floating top eliminates any vapor space above the fuel that might accumulate explosive vapors. The sides typically tapered, with the greater thickness of metal towards the bottom, as much as an inch and a half (4 cm). Unlike gasoline, fuel oil is not easily ignited and fuel oil tanks were not as easy a target to destroy as might be supposed. One Japanese pilot who participated in the raid on Wheeler Field recalled strafing some nearby fuel tanks and being surprised that they refused to ignite even after several strafing runs.

Although the United States produced ample oil, there was difficulty getting oil from the production fields to areas such as the East Coast where demand was high. Oil was most economically transported via tanker in 1941, with transport by pipeline costing three times as much and transport by rail tanker car ten times as much. Once war broke out, the U-boat attacks on tankers forced heavier reliance on rail tanker cars. About 120,000 were in service in early 1942, each with a capacity of about 215 barrels. These were given priority for oil shipment, and transport over distances less than 100 miles (160 km) was shifted to tanker trucks to save the rail tanker cars for longer hauls.

The shortage of tankers and expense of rail tanker cars prompted the construction of pipelines from the Gulf Coast to the East Coast, but these were delayed by political opposition orchestrated by rail concerns. The Cole Bill authorizing government construction of the pipelines passed in the summer of 1941, and work finally began to go forward in August of that year. The Plantation pipeline from Baton Rouge, Louisiana, to Greensboro, North Carolina was completed by the time war broke out, and in June 1942, the "Big Inch" and "Little Inch" pipelines from Texas to New York were approved. Big Inch was a 24" (61 cm) pipeline, while Little Inch was a 20" (51 cm) pipeline following a somewhat longer route. Big Inch reached New York in October 1943 and Little Inch reached Phoenixville, Pennsylvania, in February 1944. At their peaks, Big Inch moved 334.456 barrels of oil daily while Little Inch moved 239,844 barrels daily. Each required about 80 megawatts of power for its pumps and heaters. (Heavy fuel oil is so viscous that it must be heated before it can be pumped.) Big Inch cost 38 cents a barrel versus 40 cents per barrel for tankers and $1.74 for rail tank cars, while Little Inch was even more economical at 24 cents per barrel. The pipelines quickly paid for themselves.

Pacific oil fields


Banka Penang
Cut Bank

Huntington Beach









Santa Fe Springs







Ballantine (1947)

Barnhart (1987)

Bradley et al. (1992)

Cohen (1949)

Collingham (2011) (2006; accessed 2012-8-6)

Evans and Peattie (1997)

Hastings (2007)

Hsiung and Levine (1992)

Klein (2013)

Miller (2007)

Parillo (1993)

Van Royen and Bowles (1952)

Werneth (2008)

Willmott (1982)

Zimm (2011)

Valid HTML 4.01 Transitional