Gordon L. Rottman 
Japanese Pacific Island Defenses 1941 45 [PDF ebook] 

The prolonged and bloody fighting for control of the Japanese occupied Pacific islands in World War II is a key point in 20th-century warfare. No two islands were alike in the systems and nature of their defensive emplacements, and local improvization and command preferences affected both materials used and defensive models. This title details the establishment, construction and effectiveness of Japanese temporary and semi-permanent crew-served weapons positions and individual and small-unit fighting positions. Integrated obstacles and minefields, camouflage and the changing defensive principles are also covered.