 Throughout the campaign, the Japanese used Mount Austen (called Bear Height by the Japanese and Mount Mambulu by the local Solomon Islanders), located west of the Lunga River and about 6 mi (9.7 km) from Henderson Field, to observe the American defenses around Lunga Point. Emplaced artillery on Mount Austen delivered harassing fire on Henderson Field. The hill was also used as a defensive point to protect their positions around the upper Matanikau valley as well as to protect the Maruyama Road, which was a trail used by the Japanese to move men and supplies into the interior of the island. Mount Austen — with a summit of 1,514 ft (461 m) — was not a single peak, but a mixed ridgeline of rocky exposed and jungle-covered ridges and hilltops. After the defeat in the Battle for Henderson Field, the Army Section of Imperial General Headquarters directed Hyakutake to increase the numbers of troops and artillery emplaced on the ridgeline to help prepare for the next planned attack on the Americans. Therefore, Hyakutake directed some of the units that were retreating from the Henderson Field battle area to fortify Mount Austen and nearby hilltops. The forces deployed to Mount Austen included the 124th Infantry Regiment under Colonel Akinosuka Oka and several artillery units. Later, surviving troops from the 230th Infantry Regiment — which had taken heavy losses during the Koli Point action and subsequent retreat — joined Oka's forces around Mount Austen.
