Volume 6: Breaking the Bismarcks Barrier, 22 July 1942-1 May 1944 tracks the Allies' entrance into the offensive phase of the Pacific war. Having gained crucial victories at Midway and Guadalcanal, Allied forces committed substantially increased resources to breaking the Bismarcks barrier, a formidable net of Japanese air and naval bases stretching from the central Solomons to New Guinea, controlling all shipping between the Indian and Pacific Oceans.