Actions Along the Matanikau

Marines cross the Matanikau River aboard a permanent ferry, complete with landing stages at both ends. The raft was fashioned by Marine engineers from 55-gallon fuel drums. (Official USMC photo)

The Actions along the Matanikau—sometimes referred to as the Second and Third Battles of the Matanikau—were two separate but related engagements, which took place in the months of September and October 1942, among a series of engagements between the United States and Imperial Japanese naval and ground forces around the Matanikau River on Guadalcanal (island in the south-western Pacific, northeast of Australia) during the Guadalcanal Campaign. These particular engagements—the first taking place between 23 and 27 September, and the second between 6 and 9 October—were two of the largest and most significant of the Matanikau actions.

The Matanikau River area included a peninsula called Point Cruz, the village of Kokumbona, and a series of ridges and ravines stretching inland from the coast. Japanese forces used the area to regroup from attacks against U.S. forces on the island, to launch further attacks on the U.S. defenses that guarded the Allied airfield (called Henderson Field) located at Lunga Point on Guadalcanal, as a base to defend against Allied attacks directed at Japanese troop and supply encampments between Point Cruz and Cape Esperance on western Guadalcanal, and as a location for watching and reporting on Allied activity around Henderson Field.

In the first action, elements of three U.S. Marine battalions under the command of U.S. Marine Major General Alexander Vandegrift attacked Japanese troop concentrations at several points around the Matanikau River. The Marine attacks were intended to “mop-up” Japanese stragglers retreating towards the Matanikau from the recent Battle of Edson’s Ridge, to disrupt Japanese attempts to use the Matanikau area as a base for attacks on the Marine Lunga defenses, and to destroy any Japanese forces in the area. The Japanese—under the overall command of Major General Kiyotake Kawaguchi—repulsed the Marine attacks. During the action, three U.S. Marine companies were surrounded by Japanese forces, took heavy losses, and barely escaped with assistance from a U.S. Navy destroyer and landing craft manned by U.S. Coast Guard personnel.

In the second action two weeks later, a larger force of U.S. Marines successfully crossed the Matanikau River, attacked Japanese forces under the command of newly arrived generals Masao Maruyama and Yumio Nasu, and inflicted heavy casualties on a Japanese infantry regiment. The second action forced the Japanese to retreat from their positions east of the Matanikau and hindered Japanese preparations for their planned major offensive on the U.S. Lunga defenses set for later in October 1942 that resulted in the Battle for Henderson Field.

Background

On 7 August 1942, Allied forces (primarily American) 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 secure the islands as starting points for a campaign with the eventual goal of neutralizing 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 8 August the Allied landing forces had secured Tulagi and nearby small islands, as well as an airfield, later called Henderson Field by Allied forces, under construction at Lunga Point on Guadalcanal.

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. The 17th Army, by this time heavily involved with the Japanese campaign in New Guinea, had only a few units available to send to the southern Solomons area. Of these units, 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 was embarked on transport ships near Guam. The different units began to move towards Guadalcanal immediately, but Ichiki’s regiment—being the closest—arrived first. The “First Element” of Ichiki’s unit—consisting of about 917 soldiers—landed from destroyers at Taivu Point, east of the Lunga perimeter, on 19 August, attacked the U.S. Marine defenses, and were almost completely annihilated during the resulting Battle of the Tenaru on 21 August.

Between 29 August and 7 September, Japanese destroyers (called “Tokyo Express” by Allied forces), plus a convoy of slow barges, delivered the 6,000 men of Kawaguchi’s brigade, including the rest of Ichiki’s regiment (called the Kuma Battalion) and much of the Aoba regiment, to Guadalcanal. General Kawaguchi and 5,000 of the troops landed 20 mi (32 km) east of the Lunga Perimeter at Taivu Point. The other 1,000 troops—under the command of Colonel Akinosuke Oka—landed west of the Lunga Perimeter at Kokumbona. During this time, Vandegrift continued to direct efforts to strengthen and improve the defenses of the Lunga perimeter. Between 21 August and 3 September, he relocated three Marine battalions—including the 1st Raider Battalion, under U.S. Lieutenant Colonel Merritt A. Edson (Edson’s Raiders)—from Tulagi and Gavutu to Guadalcanal.

Kawaguchi’s Center Body of 3,000 troops began their attacks on a ridge south of Henderson Field beginning on 12 September in what was later called the Battle of Edson’s Ridge. After numerous frontal assaults, Kawaguchi’s attack was repulsed with heavy losses for the Japanese, who retreated back into the jungle on 14 September. Oka’s assault in the west and the Kuma Battalion’s assault in the east were also repulsed by the U.S. Marines over the same two days. Kawaguchi’s units were ordered to withdraw west to the Matanikau Valley to join with Oka’s unit on the west side of the Lunga Perimeter. Most of Kawaguchi’s men reached the Matanikau by 20 September.

As the Japanese regrouped west of the Matanikau, 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 3rd Provisional Marine Brigade (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.

The Japanese immediately 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, too late to join Kawaguchi’s attack on the U.S. Marines. By then, though, the battalion had joined Oka’s forces near the Matanikau. Subsequent Tokyo Express runs—beginning on 15 September—brought food and ammunition—as well as 280 men from the 1st Battalion, Aoba Regiment—to Kamimbo on Guadalcanal.

U.S. Marine Lieutenant 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. Two previous raids by Marines—on 19 and 29 August—had killed some of the Japanese forces camped in that area but had failed to deny the location as an assembly area and defensive position for the Japanese forces threatening the western portion of the Marine defenses. Vandegrift, therefore, decided to conduct another series of small unit operations around the Matanikau Valley. The purpose of these operations was to “mop-up” the scattered groups of Japanese troops east of the Matanikau and to keep the main body of Japanese soldiers off-balance to prevent them from consolidating their positions so close to the main Marine defenses at Lunga Point. The first operation was assigned to the 1st Battalion, 7th Marine Regiment under Lieutenant Colonel Chesty Puller with a start date of 23 September. The operation would be supported by artillery fire from the U.S. 11th Marine Regiment.

September Action

Prelude

The U.S. Marine plan called for Puller’s battalion to march west from the Lunga perimeter, scale a large terrain feature called Mount Austen, cross the Matanikau River, and then reconnoiter the area between the Matanikau and Kokumbona village. At the same time, the 1st Raider Battalion—now under the command of Lieutenant Colonel Samuel B. Griffith—was to cross at the mouth of the Matanikau to explore the area between the river, Kokumbona, and further west towards Tassafaronga. The Marines thought that there were about 400 Japanese in that area.

The number of Japanese troops in the Matanikau Valley was actually much higher than the Marine estimate. Believing that the Allies might attempt a major amphibious landing near the Matanikau River, Kawaguchi assigned Oka’s 124th Infantry Regiment—numbering about 1,900 men—to defend the Matanikau. Oka deployed his “Maizuru” Battalion around the base of Mount Austen and along the west and east banks of the Matanikau River. The rest of Oka’s force was located west of the Matanikau, but in position to respond quickly to any Allied attacks in that area. Including other Japanese troops located near Kokumbona, total Japanese forces in the general Matanikau area numbered about 4,000.

Action

The 930 men of Puller’s battalion marched west from the Lunga perimeter early on the morning of 23 September. Later that morning, Puller’s troops chased away two Japanese patrols that were reconnoitering the Marine Lunga defenses. Puller’s battalion then camped for the night and prepared to climb Mount Austen the next day.

At 17:00 on 24 September, as Puller’s men hiked up the northeast slope of Mount Austen, they surprised and killed a bivouac of 16 Japanese soldiers. The noise from the skirmish alerted several companies of Oka’s Maizuru Battalion, who were emplaced nearby. The Maizuru troops quickly attacked Puller’s Marines, who took cover and returned fire. Acting on Oka’s orders, the Japanese slowly disengaged while withdrawing towards the Matanikau River, and the engagement was over by nightfall. The Marines counted 30 dead Japanese and had suffered 13 dead and 25 wounded. Puller radioed headquarters and requested help to evacuate the wounded. Vandegrift replied that he would send the 2nd Battalion, 5th Marine Regiment (2/5) as reinforcements the next day.

2/5—under Lieutenant Colonel David McDougal—rendezvoused with Puller’s unit early on 25 September. Puller sent his casualties back to the Lunga perimeter with three companies of his battalion and continued on with the mission with his remaining company (Company C), his headquarters staff, and 2/5, and they bivouacked for the night between Mount Austen and the Matanikau River.

On the morning of 26 September, Puller and McDougal’s troops reached the Matanikau River and attempted to cross over a bridge previously built by the Japanese that was called the “one-log bridge.” Because of resistance by about 100 Japanese defenders around the bridge, the Marines instead proceeded north along the east bank of the Matanikau to the sand spit on the coast at the mouth of the river. Oka’s troops repulsed a Marine attempt to cross the Matanikau at the sand spit as well as another attempt to cross the one-log bridge later in the afternoon. In the meantime, Griffith’s Raider battalion—along with Merritt A. Edson, commander of the 5th Marine Regiment—joined Puller and McDougal’s troops at the mouth of the Matanikau.

Edson brought with him a “hastily devised” plan of attack—primarily written by Lieutenant Colonel Merrill B. Twining, a member of Vandegrift’s division staff—that called for Griffith’s Raiders—along with Puller’s Company C—to cross the one-log bridge and then outflank the Japanese at the river mouth/sand spit from the south. At the same time, McDougal’s battalion was to attack across the sand spit. If the attacks were successful, the rest of Puller’s battalion would land by boat west of Point Cruz to take the Japanese by surprise from the rear. Aircraft from Henderson Field—as well as Marine 75 mm (2.95 in) and 105 mm (4.1 in) artillery—would provide support for the operation. The Marine offensive would begin the next day, on 27 September.

The Marine attack on the morning of 27 September did not make much headway. Griffith’s Raiders were unable to advance at the one-log bridge over the Matanikau, suffering several casualties, including the death of Major Kenneth D. Bailey and the wounding of Griffith. A flanking attempt by the Raiders further upstream also failed. The Japanese, who had reinforced their units at the mouth of the Matanikau during the night with additional companies from the 124th Infantry Regiment, repulsed the attacks by McDougal’s men.

As a result of “garbled” messages from Griffith because of a Japanese air raid on Henderson Field that disrupted the Marine communication’s net, Vandegrift and Edson believed that the Raiders had succeeded in crossing the Matanikau. Therefore, Puller’s battalion was ordered to proceed with the planned landing west of Point Cruz. Three companies of Puller’s battalion, under Major Otho Rogers, landed from nine landing craft just west of Point Cruz at 13:00. Rogers’ Marines pushed inland and occupied a ridge, called Hill 84, about 600 yd (550 m) from the landing area. Oka—recognizing the seriousness of this landing—ordered his forces to close on Rogers’ Marines from both the west and east.

Soon after occupying the ridge, Rogers’ men came under heavy fire from two directions from Oka’s forces. Major Rogers was hit by a mortar shell that blew him in half, killing him instantly. Captain Charles Kelley—commander of one of the companies—took command and deployed the Marines in a perimeter defense around the ridge to fight back. The Marines on Hill 84 were without radio communication and thus could not call for help. The Marines improvised by using white undershirts to spell out the word “H-E-L-P” on the ridge. A Cactus Air Force (the name for the Allied aircraft operating out of Henderson Field) SBD Dauntless supporting the operation spotted the undershirt message and relayed the message to Edson by radio.

Paul Moore, Jr., a Marine veteran who participated in the battle, described it:

Each... [platoon] was to run across the sandspit until they were opposite the bank, wade across the river, and attack the Japanese battalion, which was dug in with automatic weapons and hand grenades and mortars in the bank.... Well, one platoon went over and got annihilated. Another platoon went over and got annihilated. Then another... we all realized it was insane... But if you’re a Marine, you’re ordered across the goddamn beach and you go.

Edson received a message from the Raider Battalion reporting their failure to cross the Matanikau. Edson, speaking to those around him, stated, “I guess we better call them off. They can’t seem to cross the river.” Puller angrily replied, “You’re not going to throw these men away!” apparently in reference to his men trapped on the west side of the Matanikau, and “stormed” off toward the beach where, with the help of his personal signalman, Puller was able to hail the Navy destroyer USS Monssen that was supporting the operation. Once aboard Monssen, Puller and the destroyer led 10 landing craft towards Point Cruz and established communications with Kelley on the ridge by signal flag.

By this time, Oka’s troops had moved into position to completely cut off the Marines on Hill 84 from the coast. Therefore, Monssen—coordinated by Puller—began to blast a path between the ridge and the beach. After about 30 minutes of firing by the destroyer, the way was clear for the Marines to escape to the beach. Despite taking some casualties from their own artillery fire, most of the Marines made it to the beach near Point Cruz by 16:30. Oka’s troops put heavy fire on the Marines at the beach in effort to keep them from successfully evacuating, and the U.S. Coast Guard crews manning the U.S. landing craft responded with their own heavy fire to cover the Marines’ withdrawal. Under fire, the Marines boarded the landing craft and successfully returned to the Lunga perimeter, ending the action. U.S. Coast Guard Signalman First Class Douglas Albert Munro—Officer-in-Charge of the group of Higgins boats—was killed while providing covering fire from his landing craft for the Marines as they evacuated the beach and was posthumously awarded the Medal of Honor for the action, to date the only Coast Guardsman to receive the decoration.

Aftermath

The results of the action were gratifying to the Japanese, still recovering from their defeat at Edson’s Ridge two weeks prior. Oka’s troops counted 32 bodies of U.S. Marines around Hill 84, and they captured 15 rifles and several machine guns that the Marines left behind. Major General Akisaburo Futami—chief of staff for the 17th Army at Rabaul—noted in his diary that this action was “the first good news to come from Guadalcanal.”

The action—described as “an embarrassing defeat” for the U.S. Marines—resulted in “finger-pointing” among the Marine commanders as they sought to attribute blame. Puller blamed Griffith and Edson, Griffith blamed Edson, and Twining blamed Puller and Edson. Colonel Gerald Thomas—Vandegrift’s operations officer—blamed Twining. The Marines, however, learned from the experience, and the defeat was the only one of that size suffered by U.S. Marine forces during the Guadalcanal campaign.

October Action

Prelude

The Japanese continued to deliver additional forces to Guadalcanal in preparation for their planned major offensive in late October. Between 1 and 5 October, Tokyo Express runs delivered troops from the 2nd Infantry Division, including their commander, Lieutenant General Masao Maruyama. These troops consisted of units from the 4th, 16th, and 29th Infantry Regiments. In an attempt to exploit the advantage gained in the September Matanikau action, Maruyama deployed the three battalions of the 4th Infantry Regiment with additional supporting units under Major General Yumio Nasu along the west side of the Matanikau River south of Point Cruz with three companies from the 4th Infantry Regiment placed on the east side of the river. Oka’s exhausted troops were withdrawn from the immediate Matanikau area. The Japanese units east of the river were to assist in preparing positions from which heavy artillery could fire into the U.S. Marines’ perimeter around Lunga Point.

Aware of the Japanese activity around the Matanikau, the U.S. Marines prepared for another offensive in the area with the objective of driving Japanese forces west and away from the Matanikau valley. Applying lessons learned from the September action, this time the Marines prepared a carefully coordinated plan of action involving five battalions: two from the 5th Marine Regiment, two from the 7th Marine Regiment, and one from the 2nd Marine Regiment augmented with Marine scout and sniper personnel (called the Whaling Group after its commander Colonel William J. Whaling). The 5th Marine’s battalions were to attack across the mouth of the Matanikau while the other three battalions were to cross the Matanikau inland at the “one-log bridge,” turn north, and attempt to trap the Japanese forces between themselves and the coast. This time the Marine division headquarters planned to retain control of the entire operation and carefully arranged detailed support for the operation from artillery and aircraft.

Action

On the morning of 7 October, the two 5th Marine battalions attacked west from the Lunga perimeter towards the Matanikau. With direct-fire support from 75 mm guns mounted on halftracks, plus additional troops supplied by the 1st Raider Battalion, the Marines forced 200 soldiers from the Japanese 3rd Company, 1st Battalion, 4th Infantry into a small pocket on the east side of the Matanikau about 400 yd (370 m) from the river mouth. The Japanese 2nd Company tried to come to the aid of their comrades in the 3rd Company but were unable to cross the Matanikau and took casualties from Marine gunfire. Meanwhile, the two 7th Marine battalions and the Whaling Group reached positions east of the one-log bridge unopposed and bivouacked for the night.

Oblivious of the U.S. Marine offensive, General Nasu sent the 9th Company of the 4th Infantry Regiment’s 3rd Battalion across the Matanikau on the evening of 7 October. The Japanese regimental commander received word of the U.S. Marine operation about 03:00 on 8 October and immediately ordered his 1st and 2nd battalions closer to the river to counter the Marine operation.

Rain on 8 October slowed the U.S. 7th Marines and the Whaling Group as they attempted to cross the Matanikau. Near evening the U.S. 3rd Battalion 2nd Marines reached the first ridge west of the Matanikau about 1 mi (1.6 km) from Point Cruz. Opposite their position on the east bank of the river, Company H from the U.S. 2nd Battalion 7th Marines unknowingly advanced into an exposed position between the Japanese 9th Company on the east bank and the rest of the Japanese 3rd Battalion on the west bank and was forced to withdraw. As a result, the Marines halted their attack for the night and prepared to resume it the next day. Unaware that the Marines threatened their positions on the west bank of the Matanikau, the Japanese commanders—including Maruyama and Nasu—ordered their units to hold in place.

During the night, the survivors of the Japanese 3rd Company, about 150 men, attempted to break out of their pocket and cross the sandbar at the mouth of the Matanikau. The 3rd Company soldiers overran two platoons from the 1st Raiders, who were not expecting an attack from that direction, and the resulting hand-to-hand melee left 12 Marines and 59 Japanese dead. The remaining 3rd Company survivors were able to cross the river and reach friendly lines. According to Frank J. Guidone, a Marine participant in the engagement, “The fight was hours of hell. There was yelling, screams of the wounded and dying; rifle firing and machine guns with tracers piercing the night–(a) combination of fog, smoke, and the natural darkness. Truly an arena of death.”

On the morning of 9 October, the U.S. Marines renewed their offensive west of the Matanikau. The Whaling Group and the 2nd Battalion 7th Marines—commanded by Lieutenant Colonel Herman H. Hanneken—reached the shoreline around Point Cruz and trapped large numbers of Japanese troops between themselves and the Matanikau River, where the Japanese took heavy losses from U.S. artillery and aircraft bombardment. Further west, Puller’s 1st Battalion, 7th Marines trapped the Japanese 2nd Battalion, 4th Infantry in a wooded ravine. After calling for massed artillery fire into the ravine, Puller added the fire of his battalion’s mortars to create, in Puller’s words, a “machine for extermination.” The trapped Japanese troops attempted several times to escape by climbing the opposite side of the ravine, only to be cut down in large numbers by massed Marine rifle and machine gun fire. Having received intelligence information that the Japanese were planning a large surprise offensive somewhere on Guadalcanal, Vandegrift ordered all the Marine units west of the Matanikau to disengage and return to the east side of the river, which was accomplished by the evening of 9 October.

Aftermath and Significance

The Marine offensive inflicted heavy casualties on the Japanese 4th Infantry Regiment, killing around 700 Japanese troops. During this operation, 65 Marines were killed.

The same night that the U.S. Marine Matanikau operation ended on 9 October, Lieutenant General Harukichi Hyakutake—the Japanese 17th Army commander—landed on Guadalcanal to personally lead the Japanese forces in their planned large offensive scheduled for later in October. Hyakutake was immediately briefed on the loss of the Japanese positions on the east bank of the Matanikau and the annihilation of one of the 4th Infantry Regiment’s battalions. Hyakutake communicated the news directly to the Army’s General Staff in Tokyo where Lieutenant General Moritake Tanabe of the Operations Division noted in his diary that the loss of the Matanikau position was a “very bad omen” for the planned October offensive.

The Japanese determined that the reestablishment of their forces on the east bank of the Matanikau would be prohibitive in terms of the number of troops required to accomplish it. Therefore, the Japanese devised a plan of attack for their scheduled offensive that sent many of their troops on a long and arduous journey to attack the U.S. Lunga perimeter from inland. The march—which began on 16 October—exhausted the Japanese troops involved to such an extent that it was later considered as one of the major factors in the decisive Japanese defeat in the subsequent Battle for Henderson Field from 23–26 October 1942. Thus, the failure of the Japanese to gain and hold a strong position on the Matanikau proved to have lasting strategic consequences in the battle for Guadalcanal, significantly contributing to the ultimate Allied victory in the campaign.

U.S. Marine patrol crosses the Matanikau River on Guadalcanal, probably in late September or early October 1942.

Dead soldiers from the Japanese 2nd Battalion, 4th Infantry Regiment lie piled in a ravine on Guadalcanal after being killed by mortar and small arms fire from United States Marine Corps troops of the 1st Battalion, 7th Marines under Chesty Puller on October 9, 1942.

Wreckage of the Japanese 1st Independent Tank Company on the sandbar at the mouth of the Matanikau River on Guadalcanal after the failed October 1942 offensive to take Henderson Field. The tank to the left is a Type 95 light, as is the one second from right; the other three are Type 97 mediums.

U.S. Marine 155mm howitzer fires at Japanese forces on Guadalcanal west of the Matanikau River in late October 1942.

U.S. Marine forces in action in the Matanikau area, Guadalcanal, August 19, 1942. 

Map of Matanikau action between U.S. Marines and Japanese forces, September 24-27, 1942, on Guadalcanal. 

U.S. Matanikau offensive on Guadalcanal, October 7-9, 1942.

Map of Allied positions along Matanikau and Lunga Point, Guadalcanal, October 9, 1942.

Conoley's Action, 24-26 October 1942, near the Matanikau River, Guadalcanal.

 

Battle of the Tenaru

Japanese soldiers, killed while assaulting U.S. Marine Corps positions, lie dead in a coconut grove on Guadalcanal after the Battle of the Tenaru on 21 August 1942. Two U.S. Marine Corps M3 Stuart tanks of A Company, 1st Tank Battalion, participating in the battle in late afternoon are visible in the background.

The Battle of the Tenaru, sometimes called the Battle of the Ilu River or the Battle of Alligator Creek, was a land battle between the Imperial Japanese Army and Allied ground forces that took place on August 21, 1942 on the island of Guadalcanal during the Pacific campaign of World War II. The battle was the first major Japanese land offensive during the Guadalcanal campaign.

In the battle, U.S. Marines, under the overall command of U.S. Major General Alexander Vandegrift, repulsed an assault by the “First Element” of the “Ichiki” Regiment, under the command of Japanese Colonel Kiyonao Ichiki. The Marines were defending the Lunga perimeter, which guarded Henderson Field, which was captured by the Allies in landings on Guadalcanal on August 7. Ichiki’s unit was sent to Guadalcanal in response to the Allied landings with the mission of recapturing the airfield and driving the Allied forces off the island.

Underestimating the strength of Allied forces on Guadalcanal, which at that time numbered about 11,000 personnel, Ichiki’s unit conducted a nighttime frontal assault on Marine positions at Alligator Creek on the east side of the Lunga perimeter. Ichiki’s assault was defeated with heavy losses. The Marines counterattacked Ichiki’s surviving troops after daybreak, killing many more. All but 128 of the original 917 of the Ichiki Regiment’s First Element died.

The battle was the first of three separate major land offensives by the Japanese in the Guadalcanal campaign. The Japanese realized after Tenaru that Allied forces on Guadalcanal were much greater in number than originally estimated and sent larger forces to the island for their subsequent attempts to retake Henderson Field.

Background

On August 7, 1942, U.S. forces 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, the Allied landing forces accomplished their initial objectives of securing Tulagi and nearby small islands, as well as an airfield under construction at Lunga Point on Guadalcanal, by nightfall on August 8. That night, as the transports unloaded, the Allied warships screening the transports were surprised and defeated by an Imperial fleet of seven cruisers and one destroyer, commanded by Japanese Vice Admiral Gunichi Mikawa. One Australian and three U.S. cruisers were sunk and one other U.S. cruiser and two destroyers were damaged in the Battle of Savo Island. Turner withdrew all remaining Allied naval forces by the evening of August 9 without unloading all of the heavy equipment, provisions, and troops from the transports, although most of the divisional artillery was landed, consisting of thirty-two 75 mm and 105 mm howitzers. Only five days' worth of rations were landed.

The Marines ashore on Guadalcanal initially concentrated on forming a defense perimeter around the airfield, moving the landed supplies within the perimeter, and finishing the airfield. Vandegrift placed his 11,000 troops on Guadalcanal in a loose perimeter around the Lunga Point area. In four days of intense effort, the supplies were moved from the landing beach into dispersed dumps within the perimeter. Work began on the airfield immediately, mainly using captured Japanese equipment. On August 12, the airfield was named Henderson Field after Major Lofton Henderson, a Marine aviator who had been killed at the Battle of Midway. Captured Japanese stock increased the total supply of food to 14 days' worth. To conserve the limited food supplies, the Allied troops were limited to two meals per day.

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. The 17th Army, currently heavily involved with the Japanese campaign in New Guinea, had only a few units available to send to the southern Solomons area. Of these units, 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 at sea en route to Japan from Guam. The different units began to move towards Guadalcanal immediately, but Ichiki’s regiment, being the closest, arrived first.

An aerial reconnaissance of the U.S. Marine positions on Guadalcanal on August 12 by one of the senior Japanese staff officers from Rabaul sighted few U.S. troops in the open and no large ships in the waters nearby, convincing Imperial Headquarters that the Allies had withdrawn the majority of their troops. In fact, none of the Allied troops had been withdrawn. Hyakutake issued orders for an advance unit of 900 troops from Ichiki’s regiment to be landed on Guadalcanal by fast warship to immediately attack the Allied position and reoccupy the airfield area at Lunga Point. The remaining personnel in Ichiki’s regiment would be delivered to Guadalcanal by slower transport later. At the major Japanese naval base at Truk, which was the staging point for delivery of Ichiki’s regiment to Guadalcanal, Colonel Ichiki was briefed that 2,000–10,000 U.S. troops were holding the Guadalcanal beachhead and that he should, “avoid frontal attacks.”

Ichiki and 916 of his regiment’s 2,300 troops, designated the “First Element” and carrying seven days’ supply of food, were delivered to Taivu Point, about 35 kilometers (22 miles) east of Lunga Point, by six destroyers at 01:00 on August 19. Ichiki was ordered to scout the American positions and wait for the remainder of his force to arrive. Known as the Ichiki Butai (Ichiki Detachment), they were an elite and battle-seasoned force but as was about to be discovered, they were heavily stricken with “victory disease” – overconfidence due to previous success. Ichiki was so confident in the superiority of his men that he decided to destroy the American defenders before the remaining majority of his force arrived, even writing in his journal “18 August, landing; 20 August, march by night and battle; 21 August, enjoyment of the fruit of victory.” He concocted a brazenly simple plan: march straight down the beach and through the American defenses. Leaving about 100 personnel behind as a rear guard, Ichiki marched west with the remaining 800 men of his unit and made camp before dawn about 14 kilometers (8.7 miles) east of the Lunga perimeter. The U.S. Marines at Lunga Point received intelligence that a Japanese landing had occurred and took steps to find out exactly what was happening.

Prelude

Reports to Allied forces from patrols of Solomon Islanders, including retired Sergeant Major Jacob C. Vouza of the British Solomon Islands Protectorate Constabulary, under the direction of Martin Clemens, a coastwatcher and officer in the British Solomon Islands Protectorate Defence Force (BSIPDF), along with Allied intelligence from other sources, indicated that Japanese troops were present east of Lunga Point. To investigate further, on August 19, a Marine patrol of 60 men and four native scouts, commanded by U.S. Marine Captain Charles H. Brush, marched east from the Lunga Perimeter.

At the same time, Ichiki sent forward his own patrol of 38 men, led by his communications officer, to reconnoiter Allied troop dispositions and establish a forward communications base. Around 12:00 on August 19 at Koli Point, Brush’s patrol sighted and ambushed the Japanese patrol, killing all but five of its members, who escaped back to Taivu. The Marines suffered three dead and three wounded.

Papers discovered on the bodies of some of the Japanese officers in the patrol revealed that they belonged to a much larger unit and showed detailed intelligence of U.S. Marine positions around Lunga Point. The papers did not, however, detail exactly how large the Japanese force was or whether an attack was imminent.

Now anticipating an attack from the east, the U.S. Marine forces, under the direction of General Vandegrift, prepared their defenses on the east side of the Lunga perimeter. Several official U.S. military histories identify the location of the eastern defenses of the Lunga perimeter as emplaced on the Tenaru River. The Tenaru River, however, was actually located further to the east. The river forming the eastern boundary of the Lunga perimeter was actually the Ilu River, nicknamed Alligator Creek by the Marines, a double misnomer: there are no alligators in the Solomons, only crocodiles, and Alligator “Creek” was a tidal lagoon separated from the ocean by a sandbar about 7 to 15 meters (23 to 49 ft) in width and about 30 meters (98 feet) long.

Along the west side of Alligator Creek, Colonel Clifton B. Cates, commander of the 1st Marine Regiment, deployed his 1st (LtCol Cresswell) and 2nd battalions (LtCol Pollock). To help further defend the Alligator Creek sandbar, Cates deployed 100 men from the 1st Special Weapons Battalion with two 37mm anti-tank guns equipped with canister shot. Marine divisional artillery, consisting of both 75mm and 105mm guns, pre-targeted locations on the east side and sandbar areas of Alligator Creek, and forward artillery observers emplaced themselves in the forward Marine positions. The Marines worked all day on August 20 to prepare their defenses as much as possible before nightfall.

Learning of the annihilation of his patrol, Ichiki quickly sent forward a company to bury the bodies and followed with the rest of his troops, marching throughout the night of August 19 and finally halting at 04:30 on August 20 within a few miles of the U.S. Marine positions on the east side of Lunga Point. At this location, he prepared his troops to attack the Allied positions that night.

Battle

Just after midnight on August 21, Ichiki’s main body of troops arrived at the east bank of Alligator Creek and were surprised to encounter the Marine positions, not having expected to find U.S. forces located that distance from the airfield. Nearby U.S. Marine listening posts heard “clanking” sounds, human voices, and other noises before withdrawing to the west bank of the creek. At 01:30 Ichiki’s force opened fire with machine guns and mortars on the Marine positions on the west bank of the creek, and a first wave of about 100 Imperial soldiers charged across the sandbar towards the Marines.

Marine machine gun fire and canister rounds from the 37 mm cannons killed most of the Japanese soldiers as they crossed the sandbar. A few of the Japanese soldiers reached the Marine positions, engaged in hand to hand combat with the defenders, and captured a few of the Marine front-line emplacements. Also, Japanese machine gun and rifle fire from the east side of the creek killed several of the Marine machine-gunners. A company of Marines, held in reserve just behind the front line, attacked and killed most, if not all, of the remaining Japanese soldiers that had breached the front line defenses, ending Ichiki’s first assault about an hour after it had begun.

At 02:30 a second wave of about 150 to 200 Japanese troops again attacked across the sandbar and was again almost completely wiped out. At least one of the surviving Imperial officers from this attack advised Ichiki to withdraw his remaining forces, but Ichiki declined to do so.

As Ichiki’s troops regrouped east of the creek, Japanese mortars bombarded the Marine lines. The Marines answered with 75 mm artillery barrages and mortar fire into the areas east of the creek. At about 05:00, another wave of Japanese troops attacked, this time attempting to flank the Marine positions by wading through the ocean surf and attacking up the beach into the west bank area of the creek bed. The Marines responded with heavy machine gun and artillery fire along the beachfront area, again causing heavy casualties among Ichiki’s attacking troops and causing them to abandon their attack and withdraw back to the east bank of the creek. For the next couple of hours, the two sides exchanged rifle, machine gun, and artillery fire at close range across the sandbar and creek.

In spite of the heavy losses his force had suffered, Ichiki’s troops remained in place on the east bank of the creek, either unable or unwilling to withdraw. At daybreak on August 21, the commanders of the U.S. Marine units facing Ichiki’s troops conferred on how best to proceed, and they decided to counterattack. The 1st Battalion, 1st Marine Regiment, under Lieutenant Colonel Leonard B. Cresswell, crossed Alligator Creek upstream from the battle area, enveloped Ichiki’s troops from the south and east, cutting off any avenue for retreat, and began to “compress” Ichiki’s troops into a small area in a coconut grove on the east bank of the creek.

Aircraft from Henderson Field strafed Japanese soldiers that attempted to escape down the beach and, later in the afternoon, five Marine M3 Stuart tanks attacked across the sandbar into the coconut grove. The tanks swept the coconut grove with machine gun and canister cannon fire, as well as rolling over the bodies, both alive and dead, of any Japanese soldiers unable or unwilling to get out of the way. When the tank attack was over, Vandegrift wrote that, “the rear of the tanks looked like meat grinders.”

By 17:00 on August 21, Japanese resistance had ended. Colonel Ichiki was either killed during the final stages of the battle, or performed ritual suicide (seppuku) shortly thereafter, depending on the account. As curious Marines began to walk around looking at the battlefield, some wounded Japanese troops shot at them, killing or wounding several Marines. Thereafter, Marines shot and/or bayoneted any Japanese soldier lying on the ground that moved, although about 15 injured and unconscious Japanese soldiers were taken prisoner. About 30 of the Japanese troops escaped to rejoin their regiment’s rear echelon at Taivu Point.

Aftermath

For the U.S. and its allies, the victory in the Tenaru battle was psychologically significant in that Allied soldiers, after a series of defeats by Japanese Army units throughout the Pacific and east Asia, now knew that they could defeat the Imperial Armies in a land battle. The battle also set another precedent that would continue throughout the war in the Pacific, which was the reluctance of defeated Japanese soldiers to surrender and their efforts to continue killing Allied soldiers, even as the Japanese soldiers lay dying on the battlefield. On this subject Vandegrift remarked, “I have never heard or read of this kind of fighting. These people refuse to surrender. The wounded wait until men come up to examine them...and blow themselves and the other fellow to pieces with a hand grenade.” Robert Leckie, a Guadalcanal veteran, recalls the aftermath of the battle in his book Helmet For My Pillow, “Our regiment had killed something like nine hundred of them. Most lay in clusters or heaps before the gun pits commanding sandspit, as though they had not died singly but in groups. Moving among them were the souvenir hunters, picking their way delicately as though fearful of booby traps, while stripping the bodies of their possessions.”

The battle was also psychologically significant in that Imperial soldiers believed in their own invincibility and superior spirit. By August 25, most of Ichiki’s survivors reached Taivu Point and radioed Rabaul to tell 17th Army headquarters that Ichiki’s detachment had been “almost annihilated at a point short of the airfield.” Reacting with disbelief to the news, Japanese Army headquarters officers proceeded with plans to deliver additional troops to Guadalcanal to reattempt to capture Henderson Field. The next major Japanese attack on the Lunga perimeter occurred at the Battle of Edson’s Ridge about three weeks later, this time employing a much larger force than had been employed in the Tenaru battle.

Depictions

The Battle of the Tenaru is a key part of the 1945 biographical film on Al Schmid, Pride of the Marines. The brunt of the Japanese assault was borne by Marines Cpl. Lee Diamond, PFC. John Rivers and Pvt. Albert Schmid. The three were credited with 200 Japanese killed in action (KIA). Awarded the Navy Cross (America’s second highest decoration) for their actions, the trio paid dearly. Rivers lost his life, while Schmid and Diamond suffered horrendous wounds. Schmid lost sight in one eye and was left with very little in the other. Shot in his arm early in the fight, Diamond’s arms and hands were also ripped by the same grenade which blinded Schmid. In 2010, the battle became the climax of the first episode of Steven Spielberg’s and Tom Hanks’ miniseries, The Pacific.

Dead Japanese soldiers lie on the sandbar at the mouth of Alligator Creek on Guadalcanal on August 21, 1942 after being killed by U.S. Marines during the Battle of the Tenaru.

Japanese Colonel Ichiki, commander of the battalion defeated in the Battle of the Tenaru River on August 21, 1942. He committed suicide shortly after the battle ended.

British Solomons Island’s Protectorate district officer and coastwatcher Martin Clemens (center standing) with members of the British Solomon Islands Protectorate Defence Force, who served as scouts and guides for Allied forces throughout the Guadalcanal campaign.

Native Solomon Islanders, under the direction of Martin Clemens, guide U.S. Marines on a patrol along the Tenaru River on Guadalcanal, August 1942.

Battle of Tenaru River (Ilu action), August 21, 1942, between U.S. Marines and Japanese force commanded by Col Ichiki.