Guadalcanal campaign

The Guadalcanal Campaign was fought between August 7, 1942, and February 9, 1943, in the Pacific theatre of World War II. This campaign, which was a decisive and strategically important campaign of World War II, was fought on the ground, at sea, and in the air between Allied forces against Imperial Japanese forces. The fighting took place on and around the island of Guadalcanal in the southern Solomon Islands, and was the first major offensive launched by Allied forces against the Empire of Japan.
On August 7, 1942, Allied forces, mainly from the United States, started landings on the islands of Guadalcanal, Tulagi, and Florida in the southern Solomons with the aim to make supply routes between the U.S., Australia, and New Zealand safer.
The Battle of Guadalcanal was one of the first long campaigns in the Pacific.
Background
Strategic considerations
On 7 December 1941, Japanese forces attacked the neutral United States Pacific Fleet at Pearl Harbor, Hawaii. The attack killed almost 2,500 people and damaged much of the US battleship fleet, starting a war between the two nations next day. The initial goals of Japanese leaders were to destroy the US Navy, seize lands rich in natural resources, and establish strategic military bases to defend Japan's empire in the Pacific Ocean and Asia. To do this, Japanese forces captured the Philippines, Thailand, Malaya, Singapore, Burma, the Dutch East Indies, and many small islands. Joining the U.S. in the war against Japan were the rest of the Allied powers, several of whom, including the United Kingdom, Australia and the Netherlands had also been attacked by Japan.
The naval battle of the Coral Sea prevented a quick Japanese conquest of Australia and the Battle of Midway reduced Japan's carrier forces.
The Allies chose the southern Solomon Islands including Guadalcanal, as the first target. The Imperial Japanese Navy (IJN) had occupied Tulagi in May 1942 and had constructed a seaplane base nearby. Allied concern grew when, in early July 1942, the IJN began constructing a large airfield at Lunga Point on Guadalcanal. From there, Japanese long range bombers would threaten the East Coast of Australia. By August 1942, the Japanese had about 900 naval troops on Tulagi and nearby islands and 2,800 people on Guadalcanal. These bases would protect Japan's major base at Rabaul, threaten Allied supply and communication lines and establish base for attacks against Fiji, New Caledonia and Samoa.
The Japanese planned to send 45 fighters and 60 bombers to Guadalcanal. In 1942 these aircraft could provide air cover for Japanese naval forces advancing into the South Pacific.
The Allied plan to invade the southern Solomons was thought of by U.S. Admiral Ernest King, Commander in Chief, United States Fleet. He wanted to take the islands away from the Japanese. With Roosevelt's agreement, King also wanted to invade Guadalcanal. Because the United States supported Great Britain's idea of defeating Germany before Japan, the Pacific war had to compete for troops and resources with the European war.
Therefore US Army General George C. Marshall was against King's proposed attacks and asked who would command the operation. King replied that the Navy and Marines would do it themselves and instructed Admiral Chester Nimitz to plan the attacks. King won the argument with Marshall and the invasion went ahead.
The Guadalcanal attack would be carried out in at the same time as an Allied offensive in New Guinea under Douglas MacArthur. The goal was to capture the Admiralty Islands and the Bismarck Archipelago, including the major Japanese base at Rabaul. Eventually they would take the Philippines. The U.S. Joint Chiefs of Staff put Vice Admiral Robert L. Ghormley in command on 19 June 1942, to direct the attack in the Solomons.
Admiral Chester Nimitz, based at Pearl Harbor, was the overall Allied commander in chief for Pacific forces.
Task force
In preparation for the attack in the Pacific in May 1942, the U.S. 1st Marine Division moved from the United States to New Zealand. Other Allied land, naval and air force units were sent to other Pacific islands. The attack was codenamed Operation Watchtower, with the date set for 7 August 1942.
At first, the attacks were planned just for Tulagi and the Santa Cruz Islands, and not Guadalcanal. When the Allies discovered the Japanese airfield on Guadalcanal, its capture was added to the plan and the Santa Cruz operation was dropped. The Japanese knew Allied forces were moving but thought they were going to Australia and perhaps Port Moresby in New Guinea.
The Watchtower force, numbering 75 warships and transports (of vessels from the U.S. and Australia), assembled near Fiji on 26 July 1942. They did one rehearsal landing prior to leaving for Guadalcanal on 31 July. The commander of the Allied force was U.S. Vice Admiral Frank Fletcher (flag in aircraft carrier ). Commanding the sea and land forces was U.S. Rear Admiral Richmond K. Turner. Vandegrift led the 16,000 Allied (primarily U.S. Marine) infantry for the landings.
The troops sent to Guadalcanal were fresh from military training and armed with M1903 Springfield rifles and a 10-day supply of ammunition. To get them into battle quickly, the operation planners had reduced their supplies to only 60 days. The troops of the 1st Marine Division began referring to the coming battle as "Operation Shoestring".
Landings
Bad weather allowed the Allied force to arrive near Guadalcanal unseen by the Japanese on the night of 6 August and the morning of 7 August and take the defenders by surprise. This has sometimes been called the Midnight Raid on Guadalcanal. The landing force split into two groups, with one group attacking Guadalcanal, and the other Tulagi, Florida, and nearby islands.
Allied warships bombed the invasion beaches while U.S. carrier aircraft bombed Japanese forces on the target islands and destroyed 15 Japanese seaplanes at their base near Tulagi.
Tulagi and two nearby small islands, Gavutu and Tanambogo, were attacked by 3,000 U.S. Marines. The 886 IJN forces violently resisted the Marine attacks. With some difficulty, the Marines captured all three islands; Tulagi on 8 August, and Gavutu and Tanambogo by 9 August.
The Japanese defenders were almost all killed while the Marines had 122 killed.
The landings on Guadalcanal had much less resistance. On 7 August, 11,000 U.S. Marines came ashore on Guadalcanal and met no resistance. They stopped for the night about from the Lunga Point airfield. The next day, against little resistance, the Marines advanced to Lunga River and captured the airfield by 16:00 on 8 August.
The Japanese naval construction staff and combat troops had abandoned the airfield area and fled about west to the Matanikau River and Point Cruz area. They left behind food, supplies, construction equipment and vehicles, and 13 dead.
During the landing operations on 7 and 8 August, Japanese naval aircraft based at Rabaul, under the command of Sadayoshi Yamada, attacked the Allied forces several times, setting afire the transport USS George F. Elliot (which sank two days later) and heavily damaging the destroyer . In the air attacks over the two days, the Japanese lost 36 aircraft, while the U.S. lost 19, both in combat and to accident, including 14 carrier fighters.
After these fights, Fletcher was concerned about the losses to his carrier fighter aircraft. He was also anxious about the threat to his carriers from Japanese air attacks, and worried about his ships' fuel levels. Fletcher pulled back from the Solomon Islands area with his carrier task forces the evening of 8 August. As a result of the loss of carrier-based air cover, Turner pulled back his ships from Guadalcanal, even though less than half of the supplies and heavy equipment needed by the troops ashore had been unloaded. Turner planned, however, to unload as many supplies as possible on Guadalcanal and Tulagi throughout the night of 8 August and then depart with his ships early on 9 August.
Battle of Savo Island
That night, as the transports unloaded, two groups of Allied cruisers and destroyers, under the command of British Rear Admiral Victor Crutchley VC, were defeated by a Japanese force of seven cruisers and one destroyer from the 8th Fleet based at Rabaul and Kavieng and commanded by Japanese Vice Admiral Gunichi Mikawa.
In the Battle of Savo Island one Australian and three American cruisers were sunk and one American cruiser and two destroyers were damaged. The Japanese had moderate damage to one cruiser. Mikawa, who was unaware Fletcher was preparing to pull back with the U.S. carriers, immediately went back to Rabaul without attempting to attack the transports. Mikawa was concerned about daylight U.S. carrier air attacks if he remained in the area. Without carrier air cover, Turner decided to pull back his remaining naval forces by the evening of 9 August. This left the Marines ashore without much of the heavy equipment, supplies and troops still aboard the transports. Mikawa's decision not to attempt to destroy the Allied transport ships was a big mistake.
Initial operations
The 11,000 Marines on Guadalcanal at first set up a guard around Lunga Point and the airfield. They also moved the landed supplies ashore and finished the airfield. By 18 August the airfield was ready for operation. Five days worth of food had been landed from the transports, which, along with captured Japanese food, gave the Marines a total of 14 days worth of food. To conserve supplies, the troops were limited to two meals per day.
Allied troops got sick with dysentery soon after the landings, with one in five Marines sick by mid-August. Tropical diseases affected both sides' troops. Although some of the Korean construction workers surrendered to the Marines, most of the Japanese and Korean gathered to the west and ate coconuts. A Japanese naval outpost was also located at Taivu Point, about 35 kilometres (22 mi) east of the Lunga perimeter. On 8 August, a Japanese destroyer from Rabaul delivered 113 troops to the Matanikau position.
On the evening of 12 August, a 25-man U.S. Marine patrol landed by boat to try and find a group of Japanese troops that U.S. forces thought might be willing to surrender. Soon after the patrol landed, a nearby platoon of Japanese naval troops attacked and almost completely killed the Marine patrol.
On 19 August, Vandegrift sent three companies of the U.S. 5th Marine Regiment to attack the Japanese troops west of the Matanikau. One company attacked at the mouth of the Matanikau river while another crossed the river inland and attacked the Japanese forces in Matanikau village. The third landed by boat further west and attacked Kokumbuna village. After briefly occupying the two villages, the three Marine companies returned to the Lunga perimeter, having killed about 65 Japanese soldiers while losing four.
This was the first of several major actions around the Matanikau River during the battle.
On 20 August, the escort carrier delivered two squadrons of Marine aircraft to Henderson Field, one a squadron of 19 F4F Wildcats and the other a squadron of 12 SBD Dauntlesses. The aircraft at Henderson became known as the "Cactus Air Force" (CAF) after the Allied codename for Guadalcanal.
The Marine fighters were used the next day. There were Japanese bomber air raids almost every day. On 22 August five U.S. Army P-400 Airacobras and their pilots arrived at Henderson Field.
Battle of the Tenaru
In response to the Allied landings on Guadalcanal, the Japanese Imperial General Headquarters assigned the Imperial Japanese Army's (IJA) 17th Army at Rabaul and under the command of Lieutenant General Harukichi Hyakutake, was ordered to retake Guadalcanal. The army was to be supported by Japanese naval units, including the Combined Fleet under the command of Isoroku Yamamoto, which was headquartered at Truk. The 17th Army, at that time involved in the Japanese campaign in New Guinea, had only a few units available. The 35th Infantry Brigade under Major General Kiyotake Kawaguchi was at Palau. The 4th (Aoba) Infantry Regiment was in the Philippines and the 28th (Ichiki) Infantry Regiment, under the command of Colonel Kiyonao Ichiki, was on transport ships near Guam.
The different units began to move towards Guadalcanal. Ichiki's unit, consisting of about 917 soldiers, landed from destroyers at Taivu Pointbafter midnight on 19 August, then made a night march west toward the Marines. The Ichiki regiment was named after its commanding officer.
Ichiki thought that there were not that many Allied soldiers on Guadalcanal. Ichiki's soldiers attacked Marine positions at Alligator Creek in the early morning hours of 21 August. Ichiki's attack was defeated with heavy Japanese losses in what became known as the Battle of the Tenaru. In the day, the Marines attacked Ichiki's surviving troops, killing many more of them.
The dead included Ichiki, though it has been claimed that he committed suicide after realizing his defeat, rather than dying in combat. In total, all but 128 of the original 917 members of the Ichiki Regiment's force were killed in the battle. The survivors returned to Taivu Point, notified 17th Army headquarters of their defeat and waited for new soldiers and orders from Rabaul.
Battle of the Eastern Solomons
As the Tenaru battle was ending, more Japanese troops were already on their way. Three slow transports departed from Truk on 16 August carrying the remaining 1,400 soldiers from Ichiki's (28th) Infantry Regiment plus 500 naval marines from the 5th Yokosuka Special Naval Landing Force.
The transports were guarded by 13 warships commanded by Japanese Rear Admiral Raizo Tanaka. He planned to land the troops on Guadalcanal on 24 August. To cover the landings and retake Henderson Field from Allied forces, Yamamoto directed Chuichi Nagumo to meet with a carrier force from Truk on 21 August and head towards the southern Solomon Islands. Nagumo's force included three carriers and 30 other warships.
Three U.S. carrier task forces under Fletcher approached Guadalcanal to attack the Japanese. On 24 and 25 August, the two carrier forces fought the Battle of the Eastern Solomons, which resulted in both fleets pulling back from the area after taking some damage. Japan lost one light aircraft carrier. Tanaka's convoy, after getting heavy damage during the battle from an air attack by aircraft from Henderson Field, including the sinking of one of the transports, changed direction to the Shortland Islands in the northern Solomons. This was done to transfer the troops to destroyers for delivery to Guadalcanal.
Air battles and strengthening of the Lunga defenses
Throughout August, small numbers of U.S. aircraft and their crews continued to arrive at Guadalcanal. By the end of August, 64 aircraft of various types were stationed at Henderson Field. Air battles between the Allied aircraft at Henderson and Japanese bombers and fighters from Rabaul continued almost daily. Between 26 August and 5 September, the U.S. lost about 15 aircraft while the Japanese lost approximately 19 aircraft. More than half of the downed U.S. aircrews were rescued while most of the Japanese aircrews were never recovered. The eight-hour round trip flight from Rabaul to Guadalcanal, about total, made it hard for the Japanese to attack Henderson Field.
Australians on Bougainville and New Georgia islands were often able to warn of Japanese air strikes, allowing the U.S. fighters time to take off and attack the Japanese bombers and fighters as they approached the island.
Between 21 August and 3 September, three Marine battalions, including the 1st Raider Battalion, under Merritt A. Edson (Edson's Raiders), and the 1st Parachute Battalion from Tulagi and Gavutu went to Guadalcanal. These units added about 1,500 troops to the original 11,000 men defending Henderson Field. The 1st Parachute Battalion, which had many dead and wounded in the Battle of Tulagi and Gavutu-Tanambogo in August, was placed under Edson's command.
The other relocated battalion, the 1st Battalion, 5th Marine Regiment (1/5), was landed west of the Matanikau near Kokumbuna village on 27 August. They had the mission of attacking Japanese units in the area. They faced hot sun, and strong Japanese defenses. The next morning, the Marines found that the Japanese defenders had departed during the night, so the Marines returned to the Lunga perimeter by boat. Losses in this action were 20 Japanese and 3 Marines killed.
Small Allied naval convoys arrived at Guadalcanal on 23 August 29 August, 1 September, and 8 September. They provided the Marines at Lunga with more food, ammunition, aircraft fuel, and aircraft technicians. The 1 September convoy also brought 392 construction engineers to work on Henderson Field.
Tokyo Express
By 23 August, Kawaguchi's 35th Infantry Brigade reached Truk and was loaded onto slow transport ships for the rest of the trip to Guadalcanal. The damage done to Tanaka's convoy during the Battle of the Eastern Solomons made the Japanese decide not to deliver more troops to Guadalcanal by slow transport. Instead, ships carrying Kawaguchi's soldiers were sent to Rabaul.
From there, the Japanese planned to deliver Kawaguchi's men to Guadalcanal by destroyers. The Japanese destroyers were usually able to make round trips down (New Georgia Sound) to Guadalcanal and back in a single night throughout the campaign, minimizing their risk of Allied air attack.
The runs became known as the "Tokyo Express" to Allied Forces by the Japanese.
Delivering the troops like this made it hard to bring heavy equipment and supplies, such as heavy artillery, vehicles, and much food and ammunition to Guadalcanal. In addition, this activity used destroyers the IJN needed for commerce defense. The Allied naval commanders did not fight Japanese naval forces at night. However, any Japanese ship remaining within range of the aircraft at Henderson Field during the daylight hours, about , was in great danger from air attack. Thissituation existed for the next several months of the battle.
Between 29 August and 4 September, Japanese light cruisers, destroyers, and patrol boats were able to land almost 5,000 troops at Taivu Point, including most of the 35th Infantry Brigade, much of the Aoba (4th) Regiment, and the rest of Ichiki's regiment. General Kawaguchi, who landed at Taivu Point on 31 August Express run, was placed in command of all Japanese forces on Guadalcanal. A barge convoy took another 1,000 soldiers of Kawaguchi's brigade, under the command of Colonel Akinosuke Oka, to Kamimbo, west of the Lunga perimeter.
Battle of Edson's Ridge
On 7 September, Kawaguchi issued his attack plan to destroy enemy in the Guadalcanal Island airfield. Kawaguchi's attack plan called for his forces to do a surprise night attack. Oka's forces would attack from the west while Ichiki's Second Echelon would attack from the east. The main attack would be by Kawaguchi's group of 3,000 men in three battalions, from the south. By 7 September, most of Kawaguchi's troops began marching towards Lunga Point along the coastline. About 250 Japanese troops remained behind to guard the brigade's supply base at Taivu.
Meanwhile, scouts brought reports to the U.S. Marines of Japanese troops at Taivu near the village of Tasimboko. Edson planned a raid on the Japanese troops at Taivu. On 8 September, after being dropped-off near Taivu by boat, Edson's men captured Tasimboko as the Japanese retreated into the jungle.
In Tasimboko, Edson's troops discovered Kawaguchi's main supply depot, including large stockpiles of food, ammunition, medical supplies, and a powerful shortwave radio. After destroying everything, except some papers, the Marines returned to the Lunga perimeter. The captured documents informed the Marines that at least 3,000 Japanese troops were on the island and planning an attack.
Edson, along with Colonel Gerald C. Thomas, Vandegrift's operations officer, thought that the Japanese attack would come at a narrow, grassy, -long, coral ridge south of Henderson Field. The ridge, called Lunga Ridge, had a good approach to the airfield and it was undefended. On 11 September, the 840 men of Edson's battalion were sent onto and around the ridge.
On the night of 12 September, Kawaguchi's 1st Battalion attacked the Raiders between the Lunga River and ridge. One Marine company had to fall back to the ridge before the Japanese stopped their attack for the night. The next night Kawaguchi had to battle Edson's 830 Raiders with 3,000 troops of his brigade and artillery. The Japanese attack began just after nightfall with Kawaguchi's 1st battalion attacking Edson's right side to the west of the ridge. After breaking through the Marine defences, the attack was eventually stopped by Marine units guarding the northern part of the ridge.
Two companies from Kawaguchi's 2nd Battalion moved up the southern edge of the ridge and pushed Edson's troops back to Hill 123 on the center part of the ridge. Throughout the night the Marines fought against Japanese attacks, some of which resulted in hand-to-hand fighting. The Marines also had artillery. Japanese groups that got past the ridge to the edge of the airfield were also sent back.
Attacks by the Kuma battalion and Oka's unit at other places were also stopped. On 14 September Kawaguchi led the survivors on a five-day march west to the Matanikau Valley to join with Oka's unit. In total Kawaguchi's forces lost about 850 killed and the Marines 104.
On 15 September Hyakutake at Rabaul learned of Kawaguchi's loss and sent the news to Imperial General Headquarters in Japan. In an emergency meeting, the top Japanese IJA and IJN command staffs decided that, Guadalcanal might develop into the most important battle of the war. The loss affected Japanese operations in other areas of the Pacific. Hyakutake realized that to send sufficient troops and supplies to defeat the Allied forces on Guadalcanal he could not support the major ongoing Japanese attacks on the Kokoda Track in New Guinea.
Hyakutake, with the agreement of General Headquarters, ordered his troops on New Guinea who were within of their goal of Port Moresby to pull back until the Guadalcanal battle was finished. Hyakutake sent more troops to Guadalcanal for another attempt to recapture Henderson Field.
Reinforcement
As the Japanese troops gathered west of the Matanikau, the U.S. forces strengthened their Lunga defenses. On 14 September Vandegrift moved another battalion, the 3rd Battalion, 2nd Marine Regiment (3/2), from Tulagi to Guadalcanal. On 18 September an Allied naval convoy delivered 4,157 men from the 3rd Provisional Marine Brigade (the 7th Marine Regiment plus a battalion from the 11th Marine Regiment and some additional support units).
The convoy also delivered 137 vehicles, tents, aviation fuel, ammunition, rations and engineering equipment to Guadalcanal. These new soldiers enabled Vandegrift, beginning on 19 September, to establish an unbroken defence around the Lunga perimeter. While protecting this convoy the aircraft carrier was sunk by the Japanese submarine southeast of Guadalcanal. For a while, this left only one Allied aircraft carrier () in the South Pacific area.
Vandegrift also removed several officers who did not meet his standards and promoted junior officers who had done well in the battles. Colonel Merritt Edson who was given command of the 5th Marine Regiment.
The air war over Guadalcanal stopped for a while. There were no Japanese air raids between 14 and 27 September due to bad weather. Both sides reinforced their air units during this time. The Japanese delivered 85 fighters and bombers to their air units at Rabaul while the U.S. brought 23 fighters and attack aircraft to Henderson Field. On 20 September the Japanese had 117 aircraft at Rabaul while the Allies had 71 aircraft at Henderson Field.
The air war got started again with a Japanese air raid on Guadalcanal on 27 September. U.S. Navy and Marine fighters from Henderson Field flew up to try to stop the air raid.
The Japanese began to prepare for their next attempt to recapture Henderson Field. The 3rd Battalion, 4th (Aoba) Infantry Regiment had landed at Kamimbo Bay on the western end of Guadalcanal on 11 September. The battalion had joined Oka's forces near the Matanikau. Deliveries by destroyers on 14, 20, 21 and 24 September brought food and ammunition as well as 280 men from the 1st Battalion, Aoba Regiment, to Kamimbo on Guadalcanal.
The Japanese 2nd and 38th Infantry Divisions were transported from the Dutch East Indies to Rabaul beginning on 13 September. The Japanese planned to transport 17,500 troops from these two divisions to Guadalcanal for the next major attack on the Lunga Perimeter set for 20 October 1942.
Actions along the Matanikau
Vandegrift was aware that Kawaguchi's troops had retreated to the area west of the Matanikau and that numerous groups of Japanese troops were in the area between the Lunga Perimeter and the Matanikau River. Vandegrift decided to attack the scattered groups of Japanese troops east of the Matanikau.
He also wanted to prevent the main group of Japanese soldiers from strengthening their positions so close to the main Marine defenses at Lunga Point.
The first U.S. Marine attack between 23 and 27 September used soldiers from three U.S. Marine battalions. The attack on Japanese forces west of the Matanikau, was defeated by Kawaguchi's troops under Akinosuke Oka's command. During the fight, three Marine companies were surrounded by Japanese forces and they had many dead and wounded. They escaped with help from the destroyer and landing craft piloted by U.S. Coast Guard personnel.
In the second attack between 6 and 9 October a larger force of Marines crossed the Matanikau River, attacked newly landed Japanese forces from the 2nd Infantry Division under the command of generals Masao Maruyama and Yumio Nasu. The Marines inflicted caused a lot of deaths and wounding for the Japanese 4th Infantry Regiment.
The second attack forced the Japanese to retreat from their positions east of the Matanikau. This caused problems with Japanese plans to do a major attack on the U.S. Lunga defenses.
Between 9 and 11 October the U.S. 1st Battalion 2nd Marines attacked two small Japanese outposts about east of the Lunga perimeter at Gurabusu and Koilotumaria near Aola Bay. The attacks killed 35 Japanese at a cost of 17 Marines and three U.S. Navy personnel.
Battle of Cape Esperance
Throughout the last week of September and the first week of October, Japanese destroyers delivered troops from the Japanese 2nd Infantry Division to Guadalcanal. The Japanese Navy promised to support the Army's attack by delivering troops, equipment, and supplies to the island and doing more air attacks on Henderson Field and sending warships to bomb the airfield.
Millard F. Harmon, commander of United States Army forces in the South Pacific, thought that U.S. Marine forces on Guadalcanal needed new soldiers if the Allies were to defend the island from the next Japanese attack. On 8 October, the 2,837 men of the 164th Infantry Regiment from the U.S. Army's Americal Division boarded ships to Guadalcanal. To protect the transports carrying the 164th to Guadalcanal, Task Force 64 was told to go with the transports. This task force consisted of four cruisers and five destroyers under U.S. Rear Admiral Norman Scott.
They were told to attack any Japanese ships that approached Guadalcanal.
Mikawa's 8th Fleet staff scheduled a large and important destroyer delivery for the night of 11 October. Two seaplane tenders and six destroyers were to deliver 728 soldiers plus artillery and ammunition to Guadalcanal. At the same time, three heavy cruisers and two destroyers under the command of Rear Admiral Aritomo Goto were to bomb Henderson Field to destroy the CAF and the airfield.
Because U.S. Navy warships had never tried to stop any Tokyo Express missions to Guadalcanal, the Japanese were not expecting any opposition from Allied naval ships that night.
Just before midnight, Scott's warships detected Goto's force on radar near Guadalcanal. Scott's force was in a position to fire on Goto's ships. Opening fire, Scott's warships sank one of Goto's cruisers and one of his destroyers, heavily damaged another cruiser, seriously wounded Goto, and forced the rest of Goto's warships to abandon the bombing mission and retreat.
One of Scott's destroyers was sunk and one cruiser and another destroyer were heavily damaged. The Japanese supply convoy unloaded at Guadalcanal and began its return journey without being discovered by Scott's force. Later on the morning of 12 October, four Japanese destroyers from the supply convoy turned back to help Goto's damaged warships.
Air attacks by CAF aircraft from Henderson Field sank two of these destroyers later that day. The convoy of U.S. Army troops reached Guadalcanal as scheduled the next day and delivered its cargo and passengers to the island.
Battleship bombing of Henderson Field
Even after the U.S. victory off Cape Esperance, the Japanese continued with plans for a large attack later in October. The Japanese decided to risk not using fast warships to deliver their men and supplies to the island.
On 13 October, a convoy of six cargo ships with eight destroyers left the Shortland Islands for Guadalcanal. The convoy carried 4,500 troops from the 16th and 230th Infantry Regiments, some naval marines, two batteries of heavy artillery, and one company of tanks.
To protect the approaching convoy from attack by CAF aircraft, Yamamoto sent two battleships from Truk to bombard Henderson Field. At 01:33 on 14 October, and , protected by one light cruiser and nine destroyers, reached Guadalcanal and fired at Henderson Field from a distance of . Over the next one hour and 23 minutes, the two battleships fired 973 shells into the Lunga perimeter, most of them falling in the area of the airfield. Many of the shells were fragmentation shells, designed to destroy land targets. The bombing heavily damaged both runways, burned almost all of the available airplane fuel, destroyed 48 of the CAF's 90 aircraft, and killed 41 men, including six CAF pilots. The battleship force then returned to Truk.
In spite of the heavy damage, Henderson soldiers were able to fix one of the runways within a few hours. Seventeen SBDs and 20 Wildcats at Espiritu Santo were flown to Henderson and U.S. Army and Marine transport aircraft began to transport airplane gasoline to Guadalcanal.
Now that the US was aware of the approach of the large Japanese convoy, the US tried to think of a way to attack the convoy before it could reach Guadalcanal. Using fuel drained from destroyed aircraft and from a hidden fuel tank in the jungle, the CAF attacked the convoy twice on the 14th, but caused no damage.
The Japanese convoy reached Guadalcanal at midnight on 14 October and began unloading. Throughout the day of 15 October, CAF aircraft from Henderson bombed and machine-gunned the unloading convoy, destroying three of the cargo ships. The remainder of the convoy departed that night, having unloaded all of the troops and about two-thirds of the supplies and equipment.
Several Japanese heavy cruisers also bombed Henderson on the nights of 14 and 15 October, destroying a few additional CAF aircraft, but not damaging the airfield.
Battle for Henderson Field
Between 1 and 17 October, the Japanese delivered 15,000 troops to Guadalcanal, giving Hyakutake 20,000 troops for his planned attack. Because they had lost their positions on the east side of the Matanikau, the Japanese decided that an attack on the U.S. defenses along the coast would be too hard. Hyakutake decided to attack from south of Henderson Field.
His 2nd Division (with troops from the 38th Division), under Lieutenant General Masao Maruyama and 7,000 soldiers in three infantry regiments was ordered to attack the American defences from the south near the east bank of the Lunga River.
The date of the attack was set for 22 October, then changed to 23 October. To try and trick the Americans from knowing about the planned attack from the south, Hyakutake's heavy artillery plus five battalions of infantry (about 2,900 men) under Major General Tadashi Sumiyoshi attacked the American defenses from the west.
The Japanese thought that there were 10,000 American troops on the island, when in there were really 23,000.
On 12 October, a group of Japanese engineers began to cut a trail, called the "Maruyama Road", from the Matanikau towards the southern portion of the U.S. Lunga perimeter. The long trail went across rivers and streams, deep ravines, steep ridges, and thick jungle.
Between 16 and 18 October, the 2nd Division began their march along the Maruyama Road.
By 23 October, Maruyama's forces were finding it hard to get through the jungle to reach the American forces. Hyakutake delayed the attack to 19:00 on 24 October. The Americans did not know that Maruyama's forces were on their way.
Sumiyoshi was told by Hyakutake's staff of the delay of the attack to 24 October. However, he was unable to contact his troops to tell them of the delay. Thus, at dusk on 23 October, two battalions of the 4th Infantry Regiment and the nine tanks of the 1st Independent Tank Company attacked on the U.S. Marine defenses at the mouth of the Matanikau.
U.S. Marine artillery, cannon, and rifle fire defeated the attacks, destroying all the tanks and killing many of the Japanese soldiers. Only a small number of Marines were killed or wounded.
Finally, late on 24 October Maruyama's forces reached the U.S. Lunga perimeter. Over two nights Maruyama's troops attacked positions defended by troops of the 1st Battalion, 7th Marines under Lieutenant Colonel Chesty Puller and the U.S. Army's 3rd Battalion, 164th Infantry Regiment, commanded by Lieutenant Colonel Robert Hall.
U.S. Marine and Army units armed with rifles, machine guns, mortars, and fire from 37 mm anti-tank guns did terrible damage to the Japanese. A few small groups of Japanese that broke through the American defenses, were all killed over the next several days.
More than 1,500 of Maruyama's troops were killed in the attacks while the Americans lost about 60 killed. Over the same two days American aircraft from Henderson Field destroying 14 Japanese aircraft and sunk a light cruiser.
Further Japanese attacks near the Matanikau on 26 October were also defeated with heavy losses for the Japanese. As a result, by 08:00 on 26 October, Hyakutake stopped the attacks and ordered his forces to retreat. About half of Maruyama's survivors were ordered to retreat back to the Matanikau Valley. The 230th Infantry Regiment under Colonel Toshinari Shoji was told to go to Koli Point, east of the Lunga perimeter.
Soldiers from the 2nd Division reached the 17th Army headquarters area at Kokumbona, west of the Matanikau on 4 November. Shoji's unit reached Koli Point and made a camp. The 2nd Division had many battle deaths, combat injuries, malnutrition, and tropical diseases. It was too weak to do any more attacks. It fought as a defensive force along the coast for the rest of the battle.
The Japanese lost 2,200 - 3,000 troops in the battle while the Americans lost around 80 killed.
Battle of the Santa Cruz Islands
At the same time that Hyakutake's troops were attacking the Lunga perimeter, Japanese aircraft carriers and other large warships led by Isoroku Yamamoto moved near the southern Solomon Islands. From this location, the Japanese naval forces hoped to defeat any Allied (primarily U.S.) naval forces, especially carrier forces. Allied naval carrier forces in the area, now under the command of William Halsey, Jr., also hoped to meet the Japanese naval forces in battle.
Nimitz had replaced Ghormley with Halsey on 18 October after deciding that Ghormley had become too negative to lead Allied forces in the South Pacific area.
The two opposing carrier forces battled each other on the morning of 26 October, in what became known as the Battle of the Santa Cruz Islands. Each side sent carrier air attacks. Allied ships had to retreat from the battle after one carrier was sunk () and another () heavily damaged. The Japanese carrier forces, however, also pulled back because of high aircraft and aircrew losses and major damage to two carriers.
The Japanese were the winners in terms of ships sunk and damaged. However, the loss by the Japanese of many experienced aircrews helped the Allies, who did not lose many aircrew. The Japanese carriers did not have any more important roles in the battle.
November land actions
To strengthen his victory in the Battle for Henderson Field, Vandegrift sent six Marine battalions, later joined by one U.S. Army battalion, on an attack west of the Matanikau. The attack was commanded by Merritt Edson and its goal was to capture Kokumbona, headquarters of the 17th Army, west of Point Cruz.
Defending the Point Cruz area were Japanese army troops from the 4th Infantry Regiment commanded by Nomasu Nakaguma. The 4th Infantry was in poor condition because of battle deaths and injuries, tropical disease, and malnutrition.
The American attack began on 1 November. It destroyed Japanese forces defending the Point Cruz area by 3 November. The Americans seemed to be close to capturing Kokumbona. Then American forces found newly landed Japanese troops near Koli Point on the eastern side of the Lunga perimeter.
To deal with these newly landed Japanese troops, Vandegrift stopped the Matanikau attack on 4 November. The Americans had 71 deaths and the Japanese around 400 killed.
At Koli Point early in the morning 3 November, five Japanese destroyers delivered 300 army troops. They were sent to help Shoji and his troops who were going to Koli Point after the Battle for Henderson Field.
When Vandegrift found out about the Japanese landing, he sent a battalion of Marines under Herman H. Hanneken to attack the Japanese at Koli. Soon after landing, the Japanese soldiers pushed Hanneken's battalion back towards the Lunga perimeter.
In response, Vandegrift ordered Puller's Marine battalion plus two of the 164th infantry battalions, along with Hanneken's battalion, to attack the Japanese forces there.
As the American troops began to move, Shoji and his soldiers began to arrive at Koli Point. Beginning on 8 November, the American troops tried to surround Shoji's forces at Gavaga Creek near Koli Point.
Hyakutake ordered Shoji to leave his positions at Koli and rejoin Japanese forces at Kokumbona in the Matanikau area. Between 9 and 11 November, Shoji and between 2,000 and 3,000 of his men escaped into the jungle to the south. On 12 November, the Americans killed all the remaining Japanese soldiers. The Americans counted the bodies of 450-475 Japanese dead in the Koli Point area and captured most of Shoji's heavy weapons and supplies. The American forces had 40 killed and 120 wounded in the attack.
On 4 November, two companies from the 2nd Marine Raider Battalion, commanded by Lieutenant Colonel Evans Carlson landed by boat at Aola Bay, east of Lunga Point. Carlson's raiders, along with troops from the U.S. Army's 147th Infantry Regiment, were told to protect 500 Seabees as they constructed an airfield at that location. Halsey had agreed with the plan to build an airfield at Aola Bay.
The Aola airfield construction was stopped at the end of November because the land was not good for building an airfield.
On 5 November, Vandegrift ordered Carlson to attack any of Shoji's forces that had escaped from Koli Point. Carlson and his troops did a 29-day patrol from Aola to the Lunga perimeter. During the patrol, Carlson's soldierz fought several battles with Shoji's retreating forces, killing almost 500 of them, while having 16 killed themselves.
In addition to the deaths from attacks by Carlson's raiders, tropical diseases and a lack of food caused more of Shoji's men to die. By the time Shoji's forces reached the Lunga River in mid-November, about halfway to the Matanikau, only 1,300 men remained. When Shoji reached the 17th Army positions west of the Matanikau, only 700 to 800 survivors were still with him. Most of the survivors from Shoji's force joined other Japanese units defending the Mount Austen and upper Matanikau River area.
Japanese destroyer trips on 5, 7 and 9 November, delivered additional troops from the Japanese 38th Infantry Division, including most of the 228th Infantry Regiment to Guadalcanal. These fresh troops were put in the Point Cruz and Matanikau area, and they stopped attacks by American forces on 10 and 18 November. The Americans and Japanese remained facing each other along a line west of Point Cruz for the next six weeks.
Naval Battle of Guadalcanal
After the defeat in the Battle for Henderson Field, the IJA planned to try again to capture the airfield in November 1942. They needed new soldiers before the attack could start. The IJA requested help from Yamamoto to deliver the new troops to the island and to support the next attack.
Yamamoto provided 11 large transport ships to carry the remaining 7,000 troops from the 38th Infantry Division, their ammunition, food, and heavy equipment from Rabaul to Guadalcanal. He also provided a warship force that included two battleships. The two battleships, and , with special fragmentation shells, were to bomb Henderson Field on the night of 12-13 November and destroy it and the aircraft stationed there. This would allow the slow, heavy transports to reach Guadalcanal and unload safely the next day. The warship force was commanded from Hiei by recently promoted Vice Admiral Hiroaki Abe.
In early November, Allied forces learned that the Japanese were preparing again to try to capture Henderson Field. Therefore, the U.S. sent Task Force 67, a convoy carrying Marines, two U.S. Army infantry battalions, and ammunition and food to Guadalcanal on 11 November. The supply ships were protected by two task groups, commanded by Rear Admirals Daniel J. Callaghan and Norman Scott, and aircraft from Henderson Field. The ships were attacked several times on 11 and 12 November by Japanese aircraft but most were unloaded without serious damage.
U.S. aircraft spotted the approach of Abe's bombing force and warned the Allied command. Turner sent all usable combat ships under Callaghan to protect the troops ashore from the expected Japanese naval attack and troop landing. He also ordered the supply ships at Guadalcanal to leave by early evening 12 November. Callaghan's force comprised two heavy cruisers, three light cruisers, and eight destroyers.
Around 01:30 on 13 November, Callaghan's force met Abe's bombing group between Guadalcanal and Savo Island. In addition to the two battleships, Abe's force included one light cruiser and 11 destroyers. In darkness, the two warship forces opened fire. Abe's warships sank or severely damaged all but one cruiser and one destroyer in Callaghan's force and both Callaghan and Scott were killed.
Two Japanese destroyers were sunk and another destroyer and Hiei was heavily damaged. In spite of his defeat of Callaghan's force, Abe ordered his warships to pull back without bombing Henderson Field. Hiei sank later that day after air attacks by CAF aircraft and aircraft from the U.S. carrier . Because of Abe's failure to destroyHenderson Field, Yamamoto ordered the troop transport convoy to wait an additional day before heading towards Guadalcanal.
Yamamoto ordered Nobutake Kondo to assemble another bombing force using warships from Truk and Abe's force to attack Henderson Field on 15 November.
At 02:00 on 14 November, a cruiser and destroyer force under Gunichi Mikawa bombed Henderson Field. The bombing caused some damage but failed to destroy airfield or most of its aircraft. As Mikawa's force went back to Rabaul, Tanaka's transport convoy, thinking that Henderson Field was now destroyed began its trip towards Guadalcanal.
Throughout 14 November, aircraft from Henderson Field and Enterprise attacked Mikawa's and Tanaka's ships, sinking one heavy cruiser and seven of the transports. Most of the troops were rescued from the transports by Tanaka's escorting destroyers and returned to the Shortlands. After dark, Tanaka and the remaining four transports continued towards Guadalcanal as Kondo's force approached to bomb Henderson Field.
In order to attack Kondo's force, Halsey, who was low on undamaged ships, sent two battleships, and , and four destroyers from the Enterprise task force. The U.S. force, under the command of Willis A. Lee aboard Washington, reached Guadalcanal and Savo Island just before midnight on 14 November, shortly before Kondo's bombing force arrived.
Kondo's force consisted of Kirishima plus two heavy cruisers, two light cruisers, and nine destroyers. After the two forces met, Kondo's force quickly sank three of the U.S. destroyers and heavily damaged the fourth. The Japanese warships then damaged South Dakota. As Kondo's warships concentrated on South Dakota, Washington approached the Japanese ships and opened fire on Kirishima, hitting the Japanese battleship and causing serious damage. After chasing Washington towards the Russell Islands, Kondo ordered his warships to pull back without bombing Henderson Field. One of Kondo's destroyers was also sunk during the battle.
As Kondo's ships pulled back, the four Japanese transports landed near Tassafaronga on Guadalcanal at 04:00 and began unloading. At 05:55, U.S. aircraft and artillery began attacking the transports, destroying all four transports along with most of the supplies that they carried.
Only 2,000-3,000 of the army troops made it ashore. Because of the failure to deliver most of the troops and supplies, the Japanese were forced to cancel their planned November attack on Henderson Field.
On 26 November, Japanese Lieutenant General Hitoshi Imamura took command of the newly formed Eighth Area Army at Rabaul. The new command included both Hyakutake's 17th Army and the 18th Army in New Guinea.
One of Imamura's first goals was to retake Henderson Field and Guadalcanal. The Allied offensive at Buna in New Guinea, however, changed Imamura's goals.
Because the Allied attempt to take Buna was considered a more severe threat to Rabaul, Imamura delayed sending new troops to Guadalcanal to concentrate on the situation in New Guinea.
Battle of Tassafaronga
The Japanese continued to have problems in delivering enough supplies to their troops on Guadalcanal. Attempts to use only submarines the last two weeks in November did not provide enough food for Hyakutake's forces.
A separate attempt to establish bases in the central Solomons to use to send barge convoys to Guadalcanal also failed because of Allied air attacks. On 26 November, the 17th Army told Imamura that it lacked food. Some front-line units had not been supplied for six days . This forced the Japanese to return to using destroyers to deliver the necessary supplies.
Eighth Fleet sailors thought of a plan to help reduce the time that destroyers delivering supplies to Guadalcanal were exposed to Allied attack. Large oil or gas drums filled with medical supplies and food and strung together with rope. When the destroyers arrived at Guadalcanal they would cut loose the drums and a boat from shore could pick up the rope.
The Eighth Fleet's Guadalcanal Reinforcement Unit (the Tokyo Express) was told to make five deliveries to Tassafaronga on Guadalcanal using the drum method on the night of 30 November. Tanaka's unit had eight destroyers, with six destroyers carrying 200 to 240 drums of supplies each.
When Halsey learned about the Japanese supply attempt, he ordered the newly formed Task Force 67, which had four cruisers and four destroyers under the command of U.S. Rear Admiral Carleton H. Wright, to attack Tanaka's force off Guadalcanal. Two additional destroyers joined Wright's force during the day of 30 November.
At 22:40 on 30 November, Tanaka's force arrived off Guadalcanal and prepared to unload the supply barrels. Meanwhile, Wright's warships were approaching from the opposite direction. Wright's destroyers detected Tanaka's force on radar and the commander requested permission to attack with torpedoes. Wright waited four minutes before giving permission.
This allowed Tanaka's force to escape from being torpedoed. All of the American torpedoes missed their targets. At the same time, Wright's cruisers opened fire, hitting and destroying one of the Japanese destroyers. The rest of Tanaka's warships abandoned the supply mission, turned, and launched 44 torpedoes in the direction of Wright's cruisers.
The Japanese torpedoes hit and sank the U.S. cruiser and heavily damaged the cruisers , , and . The rest of Tanaka's destroyers escaped without damage, but failed to deliver any of the supplies to Guadalcanal.
By 7 December 1942, Hyakutake's forces were losing about 50 men each day from malnutrition, disease, and Allied ground or air attacks. Further attempts by Tanaka's destroyer forces to deliver supplies on 3 December 7 December, and 11 December, did not solve the supply problem. One of Tanaka's destroyers was sunk by a U.S. PT boat torpedo.
Japanese decision to withdraw
On 12 December, the Japanese Navy thought about abandoning Guadalcanal. At the same time, several army staff officers at the Imperial General Headquarters (IGH) said retaking Guadalcanal would be impossible. A group led by IJA Colonel Joichiro Sanada, chief of the IGH's operations section, visited Rabaul on 19 December and talked to Imamura and his staff.
When this group returned to Tokyo, Sanada recommended that Guadalcanal be abandoned. The IGH's top leaders agreed with Sanada's recommendation on 26 December. They ordered their staff to plan for a withdrawal from Guadalcanal. A new defense line would be set up in the central Solomons, and soldiers and weapons could be sent to the campaign in New Guinea.
On 28 December, General Hajime Sugiyama and Admiral Osami Nagano told Emperor Hirohito of the decision to withdraw from Guadalcanal. On 31 December, the Emperor agreed with the decision. The Japanese secretly began to prepare for the evacuation, called Operation Ke, scheduled to begin during January 1943.
Battle of Mount Austen, the Galloping Horse, and the Sea Horse
By December, the tired 1st Marine Division was brought back for a rest, and over the next month the U.S. XIV Corps took over operations on the island. This corps consisted of the 2nd Marine Division and the U.S. Army's 25th Infantry and Americal Divisions. U.S. Army Major General Alexander Patch replaced Vandegrift as commander of Allied forces on Guadalcanal. By January this was over 50,000 men.
On 18 December, Allied (mainly U.S. Army) forces began attacking Japanese soldiers on Mount Austen. A strong Japanese fort, called the Gifu, made the attacks hard and the Americans had to stop their attacks on 4 January.
The Allies attacking the Japanese on 10 January on Mount Austen. They also attacked two nearby ridges called the Seahorse and the Galloping Horse. The Allies captured all three by 23 January. At the same time, U.S. Marines advanced along the north coast of the island. The Americans lost about 250 killed in the operation while the Japanese suffered around 3,000 killed-about 12 to 1 in the Americans' favor.
Ke evacuation
On 14 January, destroyers delivered troops to guard the Ke evacuation. Japanese warships and aircraft moved around the Rabaul and Bougainville areas in preparation to withdraw their troops. Allied forces detected the Japanese movements, but thought they were another attempt to retake Henderson Field and Guadalcanal.
Patch, afraid of another Japanese attack, sent only a small portion of his troops to continue an attack against Hyakutake's forces. On 29 January, Halsey sent a resupply convoy to Guadalcanal protected by a cruiser task force. Sighting the cruiser task force, Japanese naval torpedo bombers attacked the task force and heavily damaged the U.S. cruiser . The next day, more torpedo aircraft attacked and sank Chicago.
Halsey ordered the remainder of the task force to return to base and directed the rest of his naval forces to take station in the Coral Sea, south of Guadalcanal, to be ready to respond to a Japanese attack.
The Japanese 17th Army withdrew to the west coast of Guadalcanal while rear guard groups stopped the American attacks. On the night of February 1, 20 destroyers from Mikawa's 8th Fleet under Shintaro Hashimoto removed 4,935 soldiers, mainly from the 38th Division, from the island. The Japanese and the Americans each lost a destroyer from air and naval attacks.
On the nights of 4 and 7 February, Hashimoto and his destroyers completed the removal of most of the remaining Japanese forces from Guadalcanal. Apart from some air attacks, Allied forces did not try to stop Hashimoto's efforts to withdraw his troops. In total, the Japanese removed 10,652 men from Guadalcanal. On 9 February, Patch realized that the Japanese were gone and declared Guadalcanal secure for Allied forces, ending the battle.
Aftermath
After the Japanese withdrawal, Guadalcanal and Tulagi were developed into major bases. These bases supported the Allied advance further up the Solomon Islands chain. In addition to Henderson Field, two additional fighter runways were constructed at Lunga Point and a bomber airfield was built at Koli Point.
Naval ports were built at Guadalcanal, Tulagi, and Florida. The anchorage around Tulagi became an important base for Allied warships and transport ships supporting the Solomon Islands campaign. Major ground units stayed in camps on Guadalcanal before being sent further up the Solomons.
After Guadalcanal the Japanese were having to defend themselves in the Pacific. The efforts to send new troops to Guadalcanal had weakened Japanese efforts in other areas. This helped the Australian and American attack in New Guinea to be successful. This led to the capture of the bases of Buna and Gona in early 1943.
In June, the Allies launched Operation Cartwheel, which aimed to cut off Rabaul and the forces centered there. This helped the South West Pacific campaign under General Douglas MacArthur. It also helped the Central Pacific island hopping campaign under Admiral Chester Nimitz. Both efforts got the Allies closer to Japan. The remaining Japanese defenses in the South Pacific area were destroyed or bypassed by Allied forces.
Significance
Resources
The Battle of Guadalcanal was one of the first long battles in the Pacific, alongside the Solomon Islands campaign. Both battles were very hard to organize for both of the nations involved. For the U.S., it had to learn how to do combat air transport. A failure to achieve air superiority forced Japan to get new troops in by barges, destroyers, and submarines, which did not work that well.
Early in the battle, the Americans lacked resources, as they lost cruisers and carriers. It took months for replacement ships to be finished.
The U.S. Navy suffered such high losses during the campaign that it refused to release total casualty figures for years. However, as the campaign continued, and the American public became more and more aware of the heroism of the American forces on Guadalcanal, more forces were sent to the area.
This was a problem for Japan as its military-industrial complex was unable to produce as much as the Americans. Thus, as the battles continued, the Japanese were losing equipment they could not replace while the Americans were replacing and even adding to their forces.
The Guadalcanal battles made Japan lose a lot of equipment and soldiers. About 25,000 experienced troops were killed during the battles. These losses meant that Japan could not achieve its goals in the New Guinea campaign. Japan also lost control of the southern Solomons and the ability to stop Allied shipping to Australia.
Japan's major base at Rabaul was threatened by Allied air power. Japanese land, air, and naval forces had been lost. The Japanese could not replace the aircraft and ships destroyed and sunk in these battles. Nor could they replace their highly trained and veteran crews, especially the naval aircrews, nearly as quickly as the Allies.
Strategic
After the victory at the Battle of Midway America was able to have naval strength in the Pacific equal to Japan's. It was only after the Allied victories in Guadalcanal and New Guinea that the Japanese attacks ended. The Guadalcanal Campaign ended all Japanese expansion attempts and placed the Allies in a position of power. This Allied victory was the first step in a winning other battles that eventually led to the surrender of Japan and the occupation of the Japanese home islands.
The "Europe first" policy of the United States had at first meant they only defended against Japanese expansion, to focus resources on defeating Germany. However, Admiral King's argument for the Guadalcanal invasion, convinced President Franklin D. Roosevelt that the Pacific War could be won as well. By the end of 1942, it was clear that Japan had lost the Guadalcanal campaign. This was very bad for Japan's plans for defending their empire.
The military victory for the Allies was important. The psychological victory was also important. The Allies had beaten Japan's best land, air, and warship forces. After Guadalcanal, Allied personnel regarded the Japanese military with much less fear than previously. In addition, the Allies began to think they could win the Pacific War.