Oil became a major strategic problem for Adolf Hitler and the Wehrmacht as Germany lost access to overseas imports from 1939. Oil was taken from stockpiles in Poland and the small Polish fields at Borislav-Drogobic; it would be taken from Norway, France, and the reserves of other occupied countries in 1940. In the interim, oil was imported from the Soviet Union under barter agreements related to the Nazi–Soviet Pact of August 23, 1939. That agreement led the French to propose bombing the Soviet fields at Baku on the Caspian Sea during the so-called Phoney War (1939–1940), a project debated intensely after Joseph Stalin launched the Finnish–Soviet War in November 1939. It was rejected by the British as likely to lead to war with the Soviet Union without changing the balance of forces vis-à-vis Nazi Germany. After BARBAROSSA cut off Soviet barter shipments from mid- 1941, the Wehrmacht relied on imports from Rumania and on German domestic and synthetic production—with the latter producing lower-grade fuels from coal in hydrogenation plants. For most of the war Germany relied principally on oil pumped from the Rumanian fields at Ploesti. Even at full production, the Rumanian wells supplied fewer than 6 million tons. The British had tried unsuccessfully to sabotage the Ploesti works and pipelines leading to Germany over the winter of 1939–1940. The USAAF failed in its initial bombing of Ploesti in 1942.
Total German oil production reached 5.7 million tons in 1941, of which 4 million tons was synthetic. The Germans briefly captured the small Soviet oil field at Maikop, holding it from August 1942 to January 1943. However, most of its facilities and wells were wrecked before the Red Army pulled out. The larger Soviet fields at Grozny were 200 miles beyond Maikop, while the main fields around Baku were 300 miles past Grozny. Nevertheless, oil at those locales lured Hitler ever deeper into the Caucasus. The Baku fields were never captured by the Wehrmacht, despite Hitler expending many divisions trying to reach them. A second Soviet oil reserve that was developed in the 1930s existed far beyond German reach, on the far side of the Volga River near Ufa. Soviet oil production was 33 million tons per annum prewar. That fell to 18 million tons in 1943, an amount still twice the tonnage available to Germany. As the Red Army advanced westward in the summer and fall of 1944, it overran two small German oil sources, a small number of wells in eastern Poland, and the oil shale of Estonia. Destruction of the Rumania wells and refineries at Ploesti by Western bombing and then Soviet occupation on August 30, 1944, meant that Hitler’s last external supply was the Nagykanizsa field in Hungary. He therefore strongly reinforced in Hungary even while the Wehrmacht and Waffen-SS were fighting desperate last-stand battles in East Prussia and Pomerania. The doomed fight to hold Hungary lasted from October 1944 to March 1945.
The Middle East was only just developing its oil capacity prior to World War II. The first well in the Middle East was drilled in Iran in 1908, overnight elevating the strategic importance of that region. Oil was first extracted from Iraq in 1927, Saudi Arabia in 1935, and Kuwait in 1938. But production was low by world standards and transport difficult and easily intercepted. Still, the presence of oil fields and some production in those areas factored into Britain’s strategic thinking. It contributed to London stationing Indian Army and other garrison forces in-country, sending in Special Operations Executive (SOE) teams and dispatching an armed expedition to topple a pro-German regime in Iraq. Britain also drew oil from Venezuela, which grew rich on its wartime exports. Oil was not discovered in volume in western Canada until 1947. Minor production around the Great Lakes did not even meet Canada’s small wartime needs. That meant British and Commonwealth forces were reliant on American oil. Like the Soviet Union, the United States had vast internal oil reserves. Americans could draw upon over 400,000 oil wells, which produced nearly 700 times as much as Japan’s puny 4,000 wells. Such abundance permitted the United States to provide its oil-deficient allies with crude and refined fuels. However, the United States was late responding to the U-boat threat to its Atlantic tanker traffic. It took months for the U.S. Navy to accept, devise, and deploy a coastal convoy system and find the escorts to make it work. Longer term, the United States solved the tanker problem by building pipelines from its Oklahoma and Texas oil fields and refineries to the large cities and ports of the northeast. Other pipelines carried fuel oil and refined products to the great ports of the west coast, for transhipment to the Pacific.
Japan had begun synthetic oil production in 1937, but a secret military study of August 1941 concluded that much more investment was needed and that even then, production would not approach Japan’s needs until 1943–1944. The Imperial Japanese Navy had already decided that lack of oil justified war in late 1941, before the U.S. Navy built up an overwhelming force in the Pacific under new appropriations bills. Lack of oil, and the sanctions on oil exports to Japan imposed by President Franklin D. Roosevelt in 1941, was a principal reason that Tokyo decided on the nanshin path: the road south led to the deep oil reserves of the Dutch East Indies. However, Japan’s inept handling of its tanker fleet during the Pacific War, notably a failure to convoy, meant that by late 1943 it could not bring Indonesian oil back to the home islands even though it still controlled the fields. The Army and Navy compounded problems by refusing to share oil stocks, not even informing each other about available reserves.