During WWII in the Pacific, the Japanese had gone from island-to-island, taking it over and setting up bases. For the US and the Allies, that meant hopping island back towards Japan, capturing as many islands as they could along the way. This created for some rather brutal fighting conditions, which you'll soon be able to recreate with the Mariana & Palau Islands Campaign Book for Bolt Action.
From the article:
The Mariana and Palau Islands campaign supplement for Bolt Action allows players to recreate the historic island-hopping battles between US and Imperial Japanese forces in the Pacific theatre that took place in 1944. Even whilst the Allies stormed the beaches of Normandy, US forces were beginning to sweep across the Pacific in their own Blitzkrieg, fighting embittered and ferocious battles across tiny strips of land against tenacious Japanese defenders.