The Battle of The Tenaru

*Note: In case anyone is wondering…Yes, I have seen (and own) the HBO miniseries, “The Pacific.” However, I am not using it as a source because it is an entertainment piece that, despite being based on historical events and people, prioritizes entertainment and individual narratives over the broader operational and strategic linkages of the Pacific War. Besides, it is easier to simply go to the original sources written by Leckie and Sledge.

The first six months of he Pacific War stand in shocking contrast to what would eventually follow, as well as the ultimate outcome of the conflict. The Imperial Japanese Army and Navy were acting as the proverbial steamroller and crushing virtually all Allied opposition in their path with relative ease. Scoring victory after victory, it seemed like it would only be a matter of time before the Japanese had firmly dug themselves into their established perimeter in their Pacific holdings to wait for the eventual American surrender. After all, the U.S. Pacific Fleet had been bombed at Pearl Harbor, the British in Singapore and Malaya had surrendered, the Netherlands East Indies had been conquered, and the American holdouts on Corregidor in the Philippines had finally surrendered in May of 1942. Victory for the Japanese was all but assured, right? Unfortunately for the Imperial Japanese Navy, a drastic change of fortune occurred at Midway in June of 1942 where four carriers were surprised and sunk with the loss of only one U.S. carrier. Subsequently, the planned operations for Midway had to be canceled. Several months later, the Americans began going on the offensive and landed Marines in the Solomon Islands on Guadalcanal. What followed would be a bloody six-month-long campaign that ultimately would see the Japanese withdraw from the island. However, before all that could happen, the Imperial Japanese Army would come to meet a harsh reality very early on in the fight for Guadalcanal. The Battle of the Tenaru was a small and seemingly insignificant action in the Guadalcanal campaign, but it serves as the perfect demonstration of the psychological makeup of the Imperial Japanese Army and its soldiers; one of death before dishonor and a gross underestimation of the capabilities of the U.S. Marines on the island. These characteristics would be repeated in many other battles and campaigns of the Pacific War as the U.S. hopped from one island stronghold to another to face a consistently stubborn and near-suicidal Japanese foe.

Japanese Response to the American Landings on Guadalcanal

American landings on Guadalcanal and the subsequent capture of Henderson airfield by the 1st Marine Division under Major General Alexander Vandegrift in early August of 1942 prompted Japanese command to organize a counterattack, particularly in light of the recent Imperial Japanese Navy (IJN) victory at the Battle of Savo Island. Imperial General Headquarters (IGHQ) erroneously assumed that the American landings on Guadalcanal were nothing more than a reconnaissance in force. However, by August 10, the IJN had discovered that a Marine division was ashore. As part of the IJN and Imperial Japanese Army’s (IJA) Central Agreement, elements of Lieutenant General Harukichi Hyakutake’s 17th Army were re-tasked from taking Port Moresby to instead retake Guadalcanal. Elements of Major General Kiyotake Kawaguchi’s 35th Infantry Brigade and the 4th and 28th Infantry Regiments (called the Aoba and Ichiki Detachments, respectively) were also made available for this task. The 28th Infantry Regiment, under Colonel Kiyonao Ichiki, was at Guam and immediately available for deployment. This also coincided with a downgrading of the numbers of Americans on the island from 1 division to about 7,000 – 8,000 due to confusion regarding reports from Japanese aircraft and submarines which were accurate versus conflicting reports from a naval staff officer of the 8th Base Force which gave very little accurate indication of the actual Marine activity on the island (Frank, 1990, p. 141 – 144).

Colonel Kiyonao Ichiki, commander of the 28th Infantry Regiment.

When briefed at Truk, Ichiki was ordered to quickly attack the seemingly disorganized Americans on the island, recapture the airfield if possible, and await reinforcements from the 35th Infantry Brigade which were expected to arrive within ten days. Ichiki was a former instructor at the Imperial Army’s Infantry school. He had a reputation for being an expert at infantry tactics, and as an impetuous, hot-blooded officer who held with the common Imperial Japanese Army’s conviction in night attacks, swords, bayonets, and the superiority of the Japanese race. Meiron and Susie Harries (1991) label Ichiki as a hasty man with “a fondness for the night attack, a low opinion of the American Marine, and an exaggerated faith in his own powers” (p. 400). Ichiki’s military career previously saw him commanding rifle units in China and he was directly responsible for the Marco Polo Bridge Incident in 1937 that precipitated the Second Sino-Japanese War that the Army had found itself bogged down in on the Asian mainland. His 28th Infantry Regiment also had a reputation, which went back to the Russo-Japanese War, as an elite unit specializing in amphibious assaults, especially after Pearl Harbor (Frank, 1990, p. 145 – 146).

Ichiki was further briefed that, should his initial attack fail, he was to take a position near the airfield and conduct repeated night assaults. He was also advised that there may be as many as 10,000 Americans on the island and to avoid direct frontal assaults. However, it is also noted that he may have disregarded this advice when he was told that the Americans were possibly preparing to withdraw. Ichiki was supremely confident that he could attack the second night after they landed and he also said that his men would only carry 250 rounds of ammo per man and seven days’ rations. Although this may have also been due to restrictions on transportation as much as his overconfidence (Frank, 1990, p. 146).

With orders in hand, Ichiki’s First Echelon of 900+ men would embark aboard six destroyers (Kagero, Hagikaze, Arashi, Tanikaze, Hamakaze, Urakaze) of Rear Admiral Raizo Tanaka’s Destroyer Squadron 2 for transport from Truk to Guadalcanal for a landing on the night of August 18 – 19. They would be followed up by Ichiki’s Second Echelon of some 1,100 men who would be transported aboard the light cruiser Jintsu and Patrol Boat 34 and Patrol Boat 35 (in reality, converted old destroyers). The Second Echelon would be joined by the 5th Yokosuka Special Naval Landing Force and would disembark on the night of August 23 – 24.  Ichiki’s First Echelon consisted of the following units:

Detachment HQ164
Battalion HQ (2nd Battalion, 28th Infantry)23
1st – 4th Infantry Companies (105 men each)420
Machine gun Company (8x heavy machine guns)110
One Platoon Battalion Gun Unit (2x 70mm guns)50
Engineer Company (1st Company, 7th Engineer Construction Regiment)150
(Frank, 1990, p. 147)

Landing Ichiki’s Detachment & First Contact

Ichiki and his men landed on Taivu Point (east of Lunga Point) at 0100 on August 19. Marching 9 miles west to Tetere, they entered the jungle at 0630 to conceal themselves. American signals intelligence discovered Ichiki’s movement to Truk and Admiral Nimitz advised that the Japanese were sending a special force to retake the island. However, this information reached Vandegrift in an ad hoc fashion by August 17 because he lacked the equipment to monitor CINCPACs intelligence broadcasts (Frank, 1990, p. 147 – 148).

The first contact with Ichiki’s unit occurred early on the 19th when Captain Charles Brush and 60 men from Company A, 1 Battalion, 1st Marines went on patrol in response to intelligence from a Catholic priest in Tetere regarding Japanese movement to the east. Ichiki had sent out a 38 man patrol under Captain Shibuya to establish a communications point near Alligator Creek. Natives warned Brush of the approaching Japanese and he set up a quick ambush. In a firefight that lasted just under one hour, Brush’s men killed all but five of Shibuya’s men with the rest escaping into the jungle for the cost of three Marines killed and three wounded. Brush gathered intelligence from the bodies that hinted at a larger Japanese Army force recently landing on the island. Having heard about the firefight, Ichiki ordered his command to begin moving. Brush returned to the Henderson perimeter with his gathered intelligence, including a Japanese map that detailed the Marine positions along Alligator Creek and artillery positions near the airfield (Frank notes that how the Japanese acquired this info is unclear and rules out Japanese observation posts on Mt. Austen because they likely were not established at this time. It is possible that it came from aerial photos, but that is uncertain). Although Bush’s captured intelligence lacked information on the size, location, and intentions of the Japanese force, it did confirm that they had come from Guam. Not wanting to immediately commit his reserve battalion in case the Japanese simultaneously attacked from the west or the sea, Vandegrift wisely decided to hunker down inside his perimeter (Frank, 1990, p. 148 – 149).

The Battle

A modern day Google Earth view of “Alligator Creek” (top left) and the Tenaru River (right).

The Battle of the Tenaru River AKA Battle of Ilu River or Battle of Alligator Creek occurred on the night of 20 – 21 August 1942 on the eastern side of the Lunga perimeter. It is actually a misnomer because the Tenaru River is further east, and what Marines call Alligator Creek, where the battle took place, is also a lie. For one thing, it is not a flowing creek, rather it is a tidal lagoon. Secondly, its reptilian denizens are not alligators, but crocodiles (there are no alligators in the Solomons). But that is what they called it. Alligator Creek is separated from the ocean by a 25 – 50 foot wide sandbar. Lieutenant Colonel Edwin Pollock’s 2nd Battalion, 1st Marines occupied the west bank from the sandbar to about 1km inland.  Specifically, one platoon from Captain Sherman’s G Company and 2 platoons from the 1st Special Weapons Battalion, totaling about 100 men, were manning guns on the west bank to sweep the sandbar and the point of land on the east bank. A 37mm gun with canister shot was also set up. Patrols routinely stood watch on the east bank of the creek as well (Frank, 1990, p. 150 – 151).

Ichiki’s plan called for his troops to move down the beach and capture the old camp of the 11th Construction Unit between Alligator Creek and the Lunga River. Once that was taken, the units would fan out and assault the airfield. Engineers would move ahead to look from crossing points along Alligator Creek, with the main body stepping off at 2000 hours on 20 August. Ichiki’s order of march was 3 rifle companies and Battalion HQ leading the Detachment HQ, Machine Gun company, and battalion gun platoon. The remaining rifle company and engineer company would be in the rear. Ichiki expected to encounter weak resistance from the Marines and said he would penetrate their positions with, “one brush of the armored sleeve.” (An old colloquial samurai saying, basically meaning, “we’ll mow ‘em down.”) (Frank, 1990, p. 151).   

Around midnight, Ichiki’s engineers briefly skirmished with the posted sentries with the colonel himself reaching Alligator Creek 30 minutes later. At 0200, after consulting with the leading company commander and the battalion commander, Major Kuramoto, a green flare lit up over the creek signaling the start of the assault led by the 2nd Company. The Marines opened up with rifles, machine guns, and 37mm canister shot on the roughly 100 men of the 2nd Company attempting to cross the sandbar. Some of the first waves made it to the west bank and past the barbed wire in front of the Marine positions to fight hand-to-hand with their bayonets drawn. Subsequent attacks by the 1st and 3rd Companies were similarly halted, but one Japanese machine gun team swam the creek, took a position in an abandoned amphibious tractor, and managed to knock out the 37mm gun. Meanwhile, Pollock reinforced the line with another platoon from G Company. Further attempts by Ichiki’s machine gun company and battalion guns failed to dislodge the Marines and were answered back by 75mm shells from the 3rd Battalion, 11th Marines. An attempt by another of Ichiki’s companies to break through the Marine defenses along the beach and through the surf was also repulsed with machine guns and artillery fire. What was left of Ichiki’s forces withdrew 200 yards into the coconut grove and the firefight continued for the rest of the night (Frank, 1990, p. 151 – 153). There is some discrepancy as to when the first wave began their attack. Frank (1990) based his generic time of 0200 from several Marine reports and diaries and further notes that other accounts say anytime between 0118-0310 (p. 679 – 680).

From his position, about 300 yards upstream (inland) from the sandbar, Robert Leckie (1957) remembers this about the battle while emplacing a machine gun:

A man says of the eruption of battle: “All hell broke loose.” The first time he says it, it is true – wonderfully descriptive. The millionth time it is said, it has been worn into meaninglessness: it has gone the way of all good phrasing, it has become cliche. But within five minutes of that first machine gun burst, of the appearance of that first enemy flare that suffused the battlefield in unearthly greenish light – and by its dying accentuated the reenveloping night – within five minutes of this, all hell broke loose. Everyone was firing, every weapon was sounding voice; but this was no orchestration, no terribly beautiful symphony of death, as decadent rear-echelon observers write. Here was cacophony; here was dissonance; here was wildness; here was the absence of rhythm, the loss of limit, for everyone fires what, when and where he chooses; here was booming, sounding, shrieking, wailing, hissing, crashing, shaking, gibbering noise. Here was hell.

(p. 78)

At daybreak, Ichiki’s remaining units showed no signs of retreating and no signs of preparing for another attack. Worried about the possibility of Japanese attacks from other directions the Marines moved to envelop Ichiki’s men. By 0700, Lieutenant Colonel Leonard Cresswell’s 1st Battalion, 1st Marines crossed the creek upstream and turned left to head towards the coast. C Company took up a blocking position further east while D Company blocked any Japanese movement south. A and B Company thus moved in to trap Ichiki in the triangle of land by the sandbar and the creek. The plan worked (Frank, 1990, p. 154 – 155).  

At first light, Leckie (1957) observed the following:

Dawn seemed to burst from a mortar tube. The two coincided; the rising bombardment of our mortars and the arrival of light. We could see, now, that the coconut grove directly opposite us had no life in it. There were bodies, but no living enemy. But to the left, toward the ocean and across the Tenaru, the remnant of this defeated Japanese attacking force was being annihilated. We could see them, running. Our mortars had got behind them. We were walking our fire in; that is dropping shells to the enemy’s rear, then lobbing the projectile steadily closer to our own lines, so that the unfortunate foe was forced to abandon cover after cover, being drawn inexorably toward our front, where he was at last flushed and destroyed.  

(p. 81)

At 1500, a platoon of light tanks crossed the sandbar to mop up any resistance on the beach and in the coconut grove. Correspondent Richard Tregaskis observed, “It was like a comedy of toys, something unbelievable, to see them knocking over palm trees which fell slowly, flushing the running figures of men from underneath their treads, following and firing at the fugitives” (as cited in Frank, 1990, p. 155). The Japanese did succeed in briefly disabling one tank with an explosive, but their labors were useless as the crew was rescued by the remaining three tanks which then returned to the east bank of the creek. By then, Cresswell’s unit was mopping up the coconut grove from the west (Frank, 1990, p. 155 – 156).

Dead Japanese soldiers in the coconut grove on the east bank of Alligator Creek. Two USMC M3 Stuart tanks can be seen in the background.

Around 1630, Ichiki ordered the regimental colors burned and committed suicide. The remaining pockets of survivors tried to flee toward the sea but were promptly cut down (Frank, 1990, p. 156). Leckie (1957) writes:

Some of the Japanese threw themselves into the channel and swam away from that grove of horror. They were like lemmings. They could not come back. Their heads bobbed like corks on the horizon. The Marines killed them from the prone position; the Marines lay on their bellies in the sand and shot them through the head. The battle was over.

(p. 83)

There is some debate as to how Ichiki met his end. Richard Frank (1990) used the Japanese Ministry of Defense’s official history version (p. 156), while Meiron and Susie Harries (1991) went with the version of Ichiki’s death as having him commit seppuku (ritual suicide) as a tank bore down on him in the palm grove (p. 400). Ichiki’s exact position during the battle, or even his remains, are left somewhat to speculation, however, all accounts agree that he died during the battle. 

Some remaining wounded Japanese attempted to take an American with them in their dying breaths by shooting at them. Seeing this as evidence of Japanese treachery, the Marines insured this would not happen again by shooting the bodies and anything that twitched (Frank, 1990, p. 156).

Japanese bodies litter the beach after the battle.

While souvenir hunting, Leckie (1957) noted that:

Dead bodies were strewn about the grove. The tropics had got at them already, and they were beginning to spill open. I was horrified at the swarms of flies…The beating of their myriad tiny wings made a dreadful low hum. The flies were in possession of the field; the tropics had won; her minions were everywhere, smacking their lips over this bounty of rotting flesh. All of my elation at the victory, all of my fanciful cockiness fled before the horror of what my eyes beheld. It could be my corrupting body the white maggots were moving over; perhaps one day it might be.

(p. 86)

Later on, Leckie (1957) heard the crocodiles eating the bodies of the dead in the creek:  

Their appetite for flesh aroused, they seemed to promenade the Tenaru daily. No enemy, we thought, would dare to swim the river with them in it; nor would he succeed if he dared. […] So the crocodiles became our darlings, we never molested them. Nor did any of us ever swim the Tenaru again.

(p. 87)
Dead soldiers of Ichiki’s Regiment partially buried in the sandbar of Alligator Creek after the battle.

All told, only one Japanese soldier surrendered and 12 wounded soldiers, including one officer, were captured. There were only two unwounded POWs. Around 777 Japanese bodies were counted. The Marines lost 44 dead and 71 wounded. Between August 22 and 29, about 128 men, what was left of Ichiki’s unit, rendezvoused back at Taivu Point. By the 22nd, news of the disaster reached the disbelieving officers in the 17th Army, 8th Fleet, and 11th Air Fleet, but it was not until the 25th when Lieutenant Sakakibara, a communications officer in Ichiki’s detachment, sent confirmation, that it was actually taken seriously (Frank, 1990, p. 156 – 158).

Aftermath & Evaluation

In strategic terms, Edward Drea (2009) notes that the Ichiki disaster was the first in a series of setbacks on Guadalcanal that ultimately resulted in the Japanese diverting resources from New Guinea, stalling the push on Port Moresby, and eventually ordered a withdrawal to Buna-Gona (p. 229).

In his book, War Without Mercy, John Dower (1986) asserts that the early rapid succession of Japanese victories in the Pacific resulted in a shock to the Americans and Europeans. This shock, combined with a mixture of propaganda and hyperbole, served to transform the Japanese from the prewar image of a diminutive and incompetent race of little yellow orientals into a sort of mythical Japanese superman who was not only a ferocious jungle fighter but also imbued with a subhuman and fanatical capacity for violence. However, their defeats at the battles of the Coral Sea and Midway in May and June of 1942, along with the Battle of the Tenaru helped to dispel the myth of the Japanese superman, at least to some degree. Still, the myths persisted for some time (p. 115). 

Richard Frank (1990) argues that the Battle of the Tenaru was one of the most important small actions in the early Pacific War due to the fact that it, “indisputably demonstrated the mortal character of the Japanese soldier” (p. 156 – 157). This is in line with Dower’s argument that the battle helped to dispel the myth of the Japanese superman.  

Tactically and psychologically, Harries (1991) notes that:

Ichiki had shown a reckless, fatalistic disdain for reconnaissance, which had revealed facts to him that he did not want to accept. He had gambled and lost at least 777 lives on his faith in his own and his army’s moral superiority.

(p. 401)

We can endlessly debate about the stupidity of Ichiki’s tactics and the impracticality of conducting bayonet charges against emplaced machine guns. Numbers and details aside, I think Frank (1990) analyzed it well when he wrote:

If Japanese strategists hoped this willingness to die to virtually the last man would cause the westerners to blanch at the brutal implications of such battle ethics, the actions of the Marines as the sun set on August 21 would have given them food for thought. If the Japanese wanted to fight to the death with no quarter asked or given, the Marines were ready to oblige them fully.

…granting that Ichiki was misinformed about the numbers and the morale of the Marines, he recklessly committed himself to attack… The destruction of Shibuya’s patrol should have injected some prudence into his conduct and afforded an honorable reason to change his plans and take advantage of the flexibility Hyakutake’s orders allowed. Ichiki sealed his fate by disdaining reconnaissance and ignoring key information concerning the open inland flank of the Marines for a frontal assault into prepared positions. But the disaster was not solely due to the character or professional shortcomings of Ichiki, for his contempt of American infantry units was shared by most officers in the Imperial Army at that time.

Perhaps even deeper than the arrogance built on easy triumphs and fanciful theories lay the code of the Japanese warrior, Bushido. …Samuel B. Griffin wrote, ‘…what happened at the Tenaru can perhaps be traced to the willingness of the Japanese… to embrace with stoicism what fate had clearly ordained. To die gloriously for the Emperor in the face of insurmountable odds was the ineluctable duty and indeed the subconscious desire of many Japanese soldiers.’

p. 157 – 158

In the end, it seems that Ichiki’s overconfidence in his capabilities and the glory of cold steel over the Americans was sorely misplaced. This overconfidence would be reflected in many other Japanese units throughout the Pacific War. Ultimately, the Battle of the Tenaru stands as an excellent small-scale study in the dissonance between the Imperial Japanese Army’s poor assessment of America’s fighting resolve and its own tactical parochialism of falling back on massed wave attacks. As the Pacific War continued on with further island-hopping campaigns the Americans would gradually face a pattern of suicidal charges and a ferocious defense from an entrenched near fanatical enemy soldier.

What if? – Ichiki lands on Midway

I will end off here with a fun fact: 

Ichiki’s regiment was originally destined for the invasion of Midway had the Imperial Japanese Navy won that battle. In their book, Shattered Sword, historians Jonathan Parshall and Anthony Tully (2005) reckon that Ichiki’s regiment would not have fared any better there had they actually went ahead with the Midway landings. This was partially due to the fact that the IJN had little in the way of an established doctrine for naval bombardment or ground attack for aircraft. Even then, naval and air bombardments generally are not as effective as you would think. Additionally, Japanese experience at conducting amphibious assaults was limited since previous amphibious landings occurred at undefended locations at night. The hostility between the Japanese Army and Navy would not have made coordination any easier as the Navy did not see the support of Army troops as one of its missions. Furthermore, the Japanese landing barges lacked radios to coordinate with the ships.

Regarding the Marines on Midway, they were even more numerous, dug-in, prepared, and heavily armed than those at Alligator Creek. In some cases, they even had reinforced concrete bunkers. In addition to 3” and 5” guns, not to mention AA guns and machine guns, the Marines had laid beach obstacles, barbed wire, mines, and over 1,500 improvised explosive devices. A platoon of M3 tanks was also hidden on the island interior. Geographically, Midway is almost entirely surrounded by a coral reef and the tides are not high enough to get boats across it. The Japanese landing craft would have had to discharge their troops on the far side of the reef and the soldiers would have had to wade at least 200 yards across the reef, completely exposed to fire. More than likely Ichiki and his men would have been mowed down by the Marines as they tried to cross the reef. Essentially, the most likely outcome would have been the same as what happened at Alligator Creek two months later (p. 487 – 489).


Dower, J. (1986). War Without Mercy: Race and Power in the Pacific War. Pantheon Books

Drea, D.J. (2009). Japan’s Imperial Army: Its Rise and Fall, 1853-1945. University Press of Kansas.

Frank, R. B. (1990). Guadalcanal: The Definitive Account of the Landmark Battle. Penguin Books.

Harries, M., & S. (1991). Soldiers of the Sun: The Rise and Fall of the Imperial Japanese Army. Random House, Inc.

Leckie, R. H. (1957). Helmet for My Pillow: From Parris Island to the Pacific. Random House, Inc.

Parshall, J., & Tully, A. (2005). Shattered Sword: The Untold Story of the Battle of Midway. Potomac Books, Inc.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s