<P> Leapfrogging, also known as island hopping, was a military strategy employed by the Allies in the Pacific War against Japan and the Axis powers during World War II . The idea was to bypass heavily fortified Japanese positions and instead concentrate the limited Allied resources on strategically important islands that were not well defended but capable of supporting the drive to the main islands of Japan . </P> <P> By the late 19th century, the U.S. had several interests in the western Pacific to defend; namely, access to the Chinese market, and its colonies--the Philippines and Guam--which the U.S. had gained as a result of the Spanish--American War (1898). After Japan's victories in the Sino - Japanese War (1894--95) and in the Russo - Japanese War of 1904, the U.S. began to regard Japan as a potential threat to its interests in the western Pacific . This antagonism was intensified by Japan's objections to an attempt to annex Hawaii to the U.S. (1893) and by Japan's objections to discrimination against Japanese immigrants both in Hawaii (1897)--on this occasion, Japan sent the cruiser Naniwa to Honolulu, Hawaii--and in California (1906, 1913). As a result, the U.S. Navy began to draft, as early as 1897, war plans against Japan, which were eventually code - named "War Plan Orange". The war plan of 1911, which was drafted under Rear Admiral Raymond P. Rodgers, included an island - hopping strategy for approaching Japan . </P>

What two major battles allowed the u.s. to start the island hopping campaign