The Matanikau Offensive, from 1–4 November 1942, sometimes referred to as the Fourth Battle of the Matanikau, was an engagement between United States (U.S.) Marine and Army and Imperial Japanese Army forces around the Matanikau River and Point Cruz area on Guadalcanal during the Guadalcanal campaign of World War II. The action was one of the last of a series of engagements between U.S. and Japanese forces near the Matanikau River during the campaign.
In the engagement, seven battalions of U.S. Marine and Army troops under the overall command of Alexander Vandegrift and tactical command of Merritt A. Edson, following up on the U.S. victory in the Battle for Henderson Field, crossed the Matanikau River and attacked Japanese Army units between the river and Point Cruz, on the northern Guadalcanal coast. The area was defended by the Japanese Army's 4th Infantry Regiment under Nomasu Nakaguma along with various other support troops, under the overall command of Harukichi Hyakutake. After inflicting heavy casualties on the Japanese defenders, U.S. forces halted the offensive and temporarily withdrew because of a perceived threat from Japanese forces elsewhere in the Guadalcanal area.
Background
Guadalcanal campaign
On 7 August 1942, Allied forces (primarily U.S.) landed on Guadalcanal, Tulagi, and Florida Islands in the Solomon Islands. The landings on the islands were meant to deny their use by the Japanese as bases for threatening the supply routes between the U.S. and Australia, and to secure the islands as starting points for a campaign with the eventual goal of isolating the major Japanese base at Rabaul while also supporting the Allied New Guinea campaign. The landings initiated the six-month-long Guadalcanal campaign.
Taking the Japanese by surprise, by nightfall on 8August the 11,000 Allied troops, under the command of Lieutenant General Alexander Vandegrift and mainly consisting of United States Marine Corps units, had secured Tulagi and nearby small islands, as well as an airfield under construction at Lunga Point on Guadalcanal. The airfield was later named Henderson Field by Allied forces. The Allied aircraft that subsequently operated out of the airfield became known as the "Cactus Air Force" (CAF) after the Allied codename for Guadalcanal. To protect the airfield, the U.S. Marines established a perimeter defense around Lunga Point.
In response to the Allied landings on Guadalcanal, the Japanese Imperial General Headquarters assigned the Imperial Japanese Army's 17th Army, a corps-sized command based at Rabaul and under the command of Lieutenant-General Harukichi Hyakutake, with the task of retaking Guadalcanal from Allied forces. Beginning on 19 August, various units of the 17th Army began to arrive on Guadalcanal with the goal of driving Allied forces from the island.
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.
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 to 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.
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. These reinforcements allowed Vandegrift, beginning on 19 September, to establish an unbroken line of defense completely around the Lunga perimeter.