The Dutch East Indies campaign of 1941–1942 was the conquest of the Dutch East Indies (present-day Indonesia) by forces from the Empire of Japan in the early days of the Pacific campaign of World War II. Forces from the Allies attempted unsuccessfully to defend the islands. The East Indies were targeted by the Japanese for their rich oil resources which would become a vital asset during the war. The campaign and subsequent three and a half year Japanese occupation was also a major factor in the end of Dutch colonial rule in the region. Background The East Indies was one of Japan's primary targets if and when it went to war because the colony possessed abundant valuable resources, the most important of which were its rubber plantations and oil fields; the colony was the fourth-largest exporter of oil in the world, behind the U.S., Iran, and Romania. The oil made the islands enormously important to the Japanese, so they sought to secure the supply for themselves. They sent four fleet carriers and a light carrier along with the four fast battleships of the , 13 heavy cruisers, and many light cruisers and destroyers to support their amphibious assaults in addition to conducting raids on cities, naval units and shipping in both that area and around the Indian Ocean. Access to oil was the main goal of the Japanese war effort, as Japan has no native source of oil; it could not even produce enough to meet even 10% of its needs, even with the extraction of oil shale in Manchuria using the Fushun process. Japan quickly lost 93 percent of its oil supply after President Franklin D. Roosevelt issued an executive order on 26 July 1941 which froze all of Japan's U.S. assets and embargoed all oil exports to Japan. In addition, the Dutch government in exile, at the urging of the Allies and with the support of Queen Wilhelmina, broke its economic treaty with Japan and joined the embargo in August. Japan's military and economic reserves included only a year and a half's worth of oil. As a U.S. declaration of war against Japan was feared if the latter took the East Indies, the Japanese planned to eliminate the U.S. Pacific Fleet, allowing them to take over the islands; this led to the attack on Pearl Harbor. Declaration of war In late November, the Netherlands government in the East