Defensive operations were considered by Japanese Imperial Army, as merely a temporary phase of combat necessitated by the momentary preponderance of the strength of hostile forces. According to Japanese doctrine, positions should be constructed on high ground immediately behind the shoreline to dominate the beaches by fire power and interdict them to hostile landing forces. Otherwise, the positions will be sited near the water line to engage the landing forces at the critical moment when they are dealing with beach obstacles and their heavy fire power is nbt available. The defensive positions will be sited to take maximum advantage of terrain and to provide both frontal and flanking fire on the beaches.

A blockhouse is a structure of heavy timbers or reinforced concrete used for military defense with sides loopholes and pierced for gunfire and often with a projecting upper story. It serves as a defensive strong point against any enemy that does not possess siege equipment or, in modern times, artillery.

Obyan Beach, Saipan, Northern Mariana Islands

[Via www.panoramio.com]

Kosrae Island, Micronesia

[Via adventurehikes.wordpress.com]

Linjiang, Baishan, Jilin, China

[Via www.panoramio.com]

 Roi-Namur, Northern Kwajalein Islands

[Via Free Republic]

Roi-Namur, Northern Kwajalein Islands

[Via www.underwaterkwaj.com]

Iwo Jima Island

[Via Christopher Marks]

Peleliu Island

[Via historyofmountneedlepie.blogspot.com]

Guam Island

[Via bcvactions.com]

Japanese 20mm Cannon Blockhouse. Saipan Islands, Northern Mariana Islands

[Via National Register of Historic Places]

Tarawa Island

[Via Steven Cone]