“Island hopping” or “leapfrogging”, was a strategy first adopted by the United States Navy under General Douglas MacArthur and Admiral Chester W. Nimitz after the Battle of Midway. This counter-offensive strike secured many small islands in the Pacific, one after another and established a line of overlapping island bases until Japanese home islands were within the range of American bombers.
The U.S troops initially targeted islands that were less defended by the Japanese. They called for preliminary bombardment by carrier-planes or land-based planes. Then, after being sufficiently “softened”, the islands were determined to be either suitable for constructing bases, or, they would have by-passed after cutting off any supplies and assistance from the homeland. In the first case, landing strips and small military bases were quickly constructed and then troops would proceed to attack other islands from these bases.
Two prongs were involved over the course of the island hopping campaign. One led by MacArthur pushed south along the New Guinea coast with assistance from Australian allies and larger land forces. The other led by Nitmitz with a smaller land force and larger fleet, advanced north and crossed central Pacific through islands such as Gilberts, Marianas, Marshalls and Carolines.
Though ultimately successful, the island hopping strategy took a long time and was very costly. U.S. troops were not familiar with the guerilla style of fighting, and the Japanese also had advantage as they previously controlled many of the islands. Many troops also succumbed illnesses such as Malaria, dysentery and skin fungus.
A clip from the documentary Payoff in the Pacific 1960