Island Hopping

Island hopping refers to the Allied strategy of bypassing strong Japanese island garrisons by taking weakly defended islands to their rear and quickly establishing airfields on these islands. This strategy, which could be considered a form of siege warfare, was developed to counter the Japanese grand strategy of establishing an impenetrable defense perimeter around a self-sufficient economic zone; allowing the Allies to batter themselves bloody against the perimeter; then negotiating a peace settlement from a position of strength.

Although some extremists in Japan spoke of occupying Alaska, Washington, and Oregon and converting the Pacific into a Japanese lake, the more realistic Japanese leaders recognized that Japan lacked the resources for a total victory over the United States. Japan thus sought to make the Pacific War a limited war, albeit on a huge scale, to be ended by a negotiated settlement on favorable terms that would allow Japan to keep her early conquests and consolidate a self-sufficient economic sphere. This proved a forlorn hope, both because the attack on Pearl Harbor so enraged the Americans that a negotiated settlement was no longer possible, and because the military strategy of perimeter defense proved flawed.

Maintaining a defensive perimeter from Burma through the Netherlands East Indies to Polynesia, then north to the Aleutians, was beyond Japan's resources. Because most of this perimeter was ocean, with bases limited to relatively small island groups, the strategy depended on the ability of the Japanese to quickly detect any assault on the perimeter, then exploit Japan's interior lines of communication to rapidly reinforce the threatened point. This looked plausible on paper. Unfortunately for the Japanese, the Allies had a crucial advantage both in overall resources and in intelligence. In almost every case, the Allies succeeded in achieving surprise and seizing their objective before the Japanese could mount an effective response.

This would still not have been sufficient to guarantee an Allied victory, had the Allies felt obligated to take every island in turn on their approach to their ultimate objectives in the heart of the Japanese Empire. Guadalcanal was first assaulted in early August 1942; the campaign in New Georgia did not end until late August 1943. It thus took over a year to seize the first two objectives on the road to Rabaul, an advance of little over 200 miles (300 km). Even allowing for the steady growth in Allied military power relative to the Japanese, this was an unacceptable rate of advance. However, the Allied command in the North Pacific had already adopted the appropriate solution to the problem, bypassing Kiska to take Attu in early 1943. This was not a deliberate strategy; the Americans lacked assault transport to take on the larger Kiska garrison and took the chance of assaulting Attu instead. However, the Japanese then evacuated their isolated garrison, allowing the Allies to take Kiska with little loss.

The concept of island hopping seems to have first been formulated by the U.S. Marines in 1938, but it was not accepted until after the experience with Attu and Kiska demonstrated its practicality. Island hopping was first deliberately employed as a strategy in the assault on Vella Lavella, which bypassed the strong Japanese garrison on Kolombangara. This was followed by the landings on Cape Torokina, which bypassed the strong Japanese garrison in the Shortland Islands and southeastern Bougainville. Nimitz took the concept to a new extreme when he overrode his entire staff to order that Kwajalein, in the center of the Marshall Islands group, be seized without first taking any of the strongly defended atolls to its east.

MacArthur also adopted the strategy, bypassing the Japanese garrison at Hansa Bay by seizing the Admiralties and then rapidly hopping northwest along the northern New Guinea coast. Though not located on separate islands, the Japanese garrison that were bypassed were effectively islands in the trackless jungles of New Guinea, which could not be quickly reinforced overland. Thus the same strategy was applicable.

The strategy depended on Allied air supremacy, since otherwise the Allied garrisons landed on islands in the Japanese rear would themselves become isolated. Maintaining air supremacy required that the Allies rapidly construct airfields on the newly seized islands. Innovations such as Marston matting made it possible to construct functioning airfields astonishingly quickly. The bypassed Japanese garrisons were then isolated by air, supplemented by local light naval forces such as PT boats.


Willmott (1982)

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