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World War II: Battle of Guadalcanal

The Allies on the Offensive


World War II: Battle of Guadalcanal

US Marines rest in the field on Guadalcanal, circa August-December 1942.

Photograph Courtesy of the US Naval Historical Center

Battle of Guadalcanal - Conflict & Date

The Battle of Guadalcanal began on August 7, 1942, during World War II (1939-1945).

Armies & Commanders


  • Major General Alexander Vandergrift
  • Major General Alexander Patch
  • up to 60,000 men


  • Lieutenant General Harukichi Hyakutake
  • General Hitoshi Imamura
  • rising to 36,200 men

Operation Watchtower

Having checked the advance of the Japanese at the Battle of the Coral Sea and decisively defeated them at the Battle of Midway, the Allies began to move to the offensive in the summer of 1942. Conceived by Admiral Ernest King, Commander-in-Chief, US Fleet, Operation Watchtower called for Allied troops to land in the Solomon Islands at Tulagi, Gavutu–Tanambogo, and Guadalcanal. Such an operation would protect the Allied lines of communication to Australia and allow for the capture of a Japanese airfield then under construction at Lunga Point, Guadalcanal.

To oversee the operation, the South Pacific Area was created with Vice Admiral Robert Ghormley in command, reporting to Admiral Chester Nimitz at Pearl Harbor. The ground forces for the invasion would be under the leadership of Major General Alexander Vandegrift, with his 1st Marine Division forming the bulk of the 16,000 troops involved. Assembling near Fiji on July 26, the Watchtower force consisted of 75 ships led by Vice Admiral Frank J. Fletcher with Rear Admiral Richmond K. Turner overseeing the amphibious forces.

Going Ashore

Approaching the area in poor weather, the Allied force remained undetected by the Japanese. On August 7, the landings began with 3,000 Marines assaulting the seaplane bases at Tulagi and Gavutu-Tanambogo. Though Japanese resistance was fierce, the islands were secured on August 8 and 9 respectively. The situation on Guadalcanal was different as Vandegrift landed with 11,000 men against minimal opposition. Pushing forward the next day, they advanced to the Lunga River, secured the airfield, and drove off the Japanese construction troops that were in the area. The Japanese retreated west to the Matanikau River.

In their haste to retreat, they left behind large quantities of food and construction equipment. At sea, Fletcher's carrier aircraft incurred losses as they battled Japanese land-based aircraft from Rabaul. Concerned about aircraft losses and his ships' fuel supplies, he withdrew from the area on the evening of August 8. That evening, Allied naval forces suffered a severe defeat at the nearby Battle of Savo Island, losing four cruisers. His air cover gone, Turner withdrew on August 9 despite the fact that not all of the troops and supplies had been landed (Map).

The Battle of Guadalcanal Begins

Ashore, Vandegrift's men worked to form a loose perimeter and completed the airfield on August 18. Dubbed Henderson Field in memory of Marine aviator Lofton Henderson, it began receiving aircraft two days later. Critical to the island's defense, the aircraft at Henderson became known as the "Cactus Air Force" (CAF) in reference to Guadalcanal's code name. During this time, the Marines began patrolling against the Japanese in the Matanikau Valley with mixed results. In response to the Allied landings, Lieutenant General Harukichi Hyakutake, commander of the 17th Army at Rabaul, began shifting troops to the island.

The first of these, under Colonel Kiyonao Ichiki, landed at Taivu Point on August 19. Advancing west, they attacked the Marines early on August 21 and were repulsed with heavy losses at the Battle of the Tenaru. The Japanese directed additional reinforcements to the area which resulted in the Battle of the Eastern Solomons. Though the battle was a draw, it forced Rear Admiral Raizo Tanaka's reinforcement convoy to turn back. As the CAF controlled the skies around the island during daylight hours, the Japanese were compelled to deliver supplies and troops to the island using destroyers.

Holding Guadalcanal

Fast enough to reach the island, unload, and escape before dawn, the destroyer supply line was dubbed the "Tokyo Express." Though effective, this method precluded the delivery of heavy equipment and weapons. His troops suffering from tropical diseases and food shortages, Vandegrift was reinforced and re-supplied in late-August and early-September. Having built up sufficient strength, Major General Kiyotake Kawaguchi attacked the Allied position at Lunga Ridge, south of Henderson Field, on September 12. In two nights of brutal fighting, the Marines held, forcing the Japanese to retreat.

On September 18, Vandegrift was further reinforced, though the carrier USS Wasp was sunk covering the convoy. An American thrust against the Matanikau was checked late in the month, but actions in early October inflicted heavy losses on the Japanese and delayed their next offensive against the Lunga perimeter. With the struggle raging, Ghormley was convinced to dispatch US Army troops to aid Vandegrift. This coincided with a large Express run scheduled for October 10/11. On that evening, the two forces collided and Rear Admiral Norman Scott won a victory at the Battle of Cape Esperance.

Not to be deterred, the Japanese sent a large convoy towards the island on October 13. To provide cover, Admiral Isoroku Yamamoto dispatched two battleships to bombard Henderson Field. Arriving after midnight on October 14, they succeeded in destroying 48 of CAF's 90 aircraft. Replacements were quickly flown to the island and CAF began attacks on the convoy that day but to no effect. Reaching Tassafaronga on the island's western shore, the convoy began unloading the next day. Returning, CAF aircraft were more successful, destroying three cargo ships. Despite their efforts, 4,500 Japanese troops landed.

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