This diagram of a typical defense system on the face of Iegusugu Pinnacle was adapted from a sketch appearing in CINCPAC-CINCPOA Weekly Intelligence, Volume 2, Number 5, 13 August 1945. The diagram does not show all the defensive positions in the area depicted and is designed only to indicate the method by which the enemy attained mobility even in fighting from positions underground. In describing this position the bulletin states: About 50 yards south of the approach road was the camouflaged entrance to a typical tunnel system within the hill. The entrance was a square log-shored shaft 30 feet deep. A smaller curved shaft which came to the surface about 15 feet away was probably designed for ventilation purposes. The main tunnel to the hill installations ran from this shaft, under the road to the first of a series of caves approximately 100 feet from the shaft entrance. This tunnel was from four to five feet high and three feet wide. Walls were reinforced with logs six to eight inches in diameter, loose coral rock on the ceilings was held in place by logs. The tunnel apparently was used for ammunition storage as well as communication.