Under Yamamoto's able subordinates, Vice Admirals Jisaburō Ozawa, Nobutake Kondō, and Ibō Takahashi, the Japanese swept the inadequate remaining American, British, Dutch and Australian naval assets from the Dutch East Indies in a series of amphibious landings and surface naval battles culminating in the Battle of the Java Sea on February 27, 1942. Along with the occupation of the Dutch East Indies came the fall of Singapore on February 15, and the eventual reduction of the remaining American-Filipino defensive positions in the Philippines on the Bataan peninsula on April 9 and Corregidor Island on May 6. The Japanese had secured their oil- and rubber-rich "southern resources area".