Henderson Field on Guadalcanal in late August 1942,

Henderson Field on Guadalcanal in late August 1942, soon after Allied aircraft began operating out of the airfield
Japanese soldiers are loaded onto the Tokyo Express.
Because of the threat by CAF aircraft based at Henderson Field, the Japanese were unable to use large, slow transport ships to deliver troops and supplies to the island. Instead, the Japanese used warships based at Rabaul and the
Shortland Islands to carry their forces to Guadalcanal. The Japanese warships, mainly light cruisers or destroyers from the Eighth Fleet under the command of
Vice Admiral Gunichi Mikawa, were usually able to make the round trip down "The Slot " to Guadalcanal and back in a single night, thereby minimizing their exposure to CAF air attack. Delivering the troops in this manner, however, prevented most of the soldiers' heavy equipment and supplies, such as heavy artillery, vehicles, and much food and ammunition, from being carried to Guadalcanal with them. These high speed warship runs to Guadalcanal occurred throughout the campaign and were later called the "Tokyo Express " by Allied forces and "Rat Transportation" by the Japanese. [9]
The first Japanese attempt to recapture Henderson Field failed when a 917-man force was defeated on 21 August in the
Battle of the Tenaru . The next attempt took place from 12–14 September, with the 6,000 soldiers under the command of Major General Kiyotake Kawaguchi being defeated in the Battle of Edson's Ridge . After their defeat at Edson's Ridge, Kawaguchi and the surviving Japanese troops regrouped west of the Matanikau River on Guadalcanal. [10]
Hyakutake immediately began to prepare for another attempt to recapture Henderson Field. The Japanese navy promised to support Hyakutake's next offensive by delivering the necessary troops, equipment, and supplies to the island, and by stepping-up air attacks on Henderson Field and sending warships to bombard the airfield.
As the Japanese regrouped, the U.S. forces concentrated on shoring up and strengthening their Lunga defenses. On 18 September, an Allied naval convoy delivered 4,157 men from the U.S. 7th Marine Regiment to Guadalcanal. This regiment had previously formed part of the 3rd Provisional Marine Brigade and was fresh from garrison duty in
Samoa. [12] These reinforcements allowed Vandegrift, beginning on 19 September, to establish an unbroken line of defense completely around the Lunga perimeter. [13]
General Vandegrift and his staff were aware that Kawaguchi's troops had retreated to the area west of the Matanikau and that numerous groups of Japanese stragglers were scattered throughout the area between the Lunga perimeter and the Matanikau River. Vandegrift, therefore, decided to conduct a series of small unit operations around the Matanikau Valley