The Battle of the Tenaru

On the night of 20–21 August 1942 a Japanese detachment under Colonel Kiyonao Ichiki attacked the eastern edge of the positions held by the US Marines, who for two weeks had been defending the airfield they had captured on Guadalcanal. The assault across a sandbar at the mouth of a shallow lagoon broke down under machine-gun and artillery fire, and in the morning the Marines surrounded the remnants of the attackers and by the afternoon had wiped them out almost to a man. Of the 917 men who went into the attack or waited in reserve, about a hundred and thirty survived. It was the first land battle of the Guadalcanal campaign and the first of three major Japanese attempts to retake the airfield.

War chronologies speak of a Japanese “counter-attack on Henderson Field” and of a separate “raid on the Tenaru (or Ilu) River”. In reality these were one and the same assault: Ichiki was heading for the airfield, and his way was barred by the line of defences along the lagoon. Under 20 August, in turn, the arrival of the first American fighter aircraft at Henderson Field is recorded. The two events are linked: the aircraft that landed on the evening of 20 August took part the next day in the destruction of Ichiki’s detachment.

An airfield without aircraft

Major General Alexander Vandegrift’s 1st Marine Division landed on 7 August near Lunga Point almost unopposed and seized the nearly finished runway that the Japanese had been building since July. The situation changed the very next night. After the defeat of the Allied covering force off Savo Island, Rear Admiral Richmond Turner withdrew the transports on 9 August, although they had not finished unloading. Left ashore on Guadalcanal were some 11,000 Marines, with their divisional artillery but with food for only a few days, without heavy engineering equipment and without air cover. Only the captured Japanese stores allowed the supplies to be stretched to about two weeks; the men got two meals a day, often of Japanese rice.

Vandegrift deployed the division in a loose perimeter around the airfield, between the Lunga River and the lagoon to the east, and turned all his strength to finishing it. The engineers worked with Japanese rollers, lorries and shovels. On 12 August the airfield was named Henderson Field in honour of Major Lofton Henderson, a Marine aviator killed at Midway, and that same day the first aircraft landed on it, a navy Catalina flying boat that had come to assess the state of the strip. Day after day, at noon, Japanese bombers came over the island from Rabaul, and at night warships shelled the shore. The Marines waited for aircraft of their own.

The first aircraft at Henderson Field

They were brought by the escort carrier Long Island, converted from a merchant ship. She carried two squadrons of Marine Aircraft Group 23: Major John L. Smith’s fighter squadron VMF-223 with 19 Grumman F4F Wildcats (some sources say 18), and Lieutenant Colonel Richard Mangrum’s dive-bomber squadron VMSB-232 with 12 Douglas SBD Dauntlesses. Many of Smith’s pilots had only just finished their training; according to aviation historians, during a stop at Efate in the New Hebrides he swapped some of the least experienced for airmen from another squadron. On 20 August Long Island closed to within a few hundred kilometres of Guadalcanal and catapulted off the aircraft, then immediately turned back south.

In the afternoon 31 aircraft landed at Henderson Field. According to the recollections of those present, Vandegrift, who for two weeks had watched Japanese aircraft bomb his positions with impunity, greeted the first pilots with tears in his eyes. The airfield as yet had no hangars, no fuel trucks and no bomb hoists: fuel was pumped by hand from drums, and bombs were loaded by muscle power. From the island’s code name, Cactus, the airmen on Guadalcanal soon became known as the “Cactus Air Force”. On 21 August they fought their first combat with Japanese Zero fighters, in which Smith claimed the first kill, and on 22 August they were joined by five P-400 fighters of the army’s 67th Fighter Squadron. Air power on Guadalcanal, though still small, was from then on to decide the fate of the whole campaign: by day it controlled the waters around the island, so that the Japanese could bring in reinforcements only at night.

The Ichiki detachment

The Japanese command reacted to the landing quickly, but on false assumptions. Responsibility for retaking the island fell to Lieutenant General Harukichi Hyakutake’s 17th Army at Rabaul, which was then committed above all to the offensive in New Guinea. The staff estimated that there were at most a few thousand Americans on the island, and a reconnaissance flight on 12 August, which spotted no large ships and no troops in the open, confirmed its belief that most of the landing force had already withdrawn. The nearest unit was Colonel Kiyonao Ichiki’s 28th Infantry Regiment, experienced from the fighting in China and originally earmarked for the landing on Midway. After the defeat of the Japanese fleet in June the regiment had been waiting on Guam, and in August it was already on its way back to Japan when it was diverted to Chuuk (Truk).

Hyakutake decided not to wait for the rest of his forces. The first echelon of the Ichiki detachment, 916 or 917 men (an infantry battalion with a machine-gun company, two infantry guns and an engineer company), was landed by six destroyers at about 1 a.m. on 19 August at Taivu Point, some 35 kilometres east of the airfield. The second part of the regiment, about 1,500 men, was to follow in slower transports covered by Rear Admiral Raizō Tanaka’s squadron. Ichiki was ordered to reconnoitre the enemy positions and wait for reinforcements, and at Chuuk he had been warned against a frontal attack. But, convinced of the superiority of his soldiers, he decided to strike at once. A timetable was later found in his diary: 18 August, landing; 20 August, night march and battle; 21 August, “enjoyment of the fruits of victory”. He left about a hundred men at Taivu and set off west along the beach with the rest.

The Americans knew of the landing from Solomon Islander scouts working for the British coastwatcher Martin Clemens. On 19 August a patrol under Captain Charles Brush ran into a Japanese reconnaissance party near Koli Point and destroyed it; on the dead officers were found maps marking the Marine positions and documents showing that a new, larger unit had arrived on the island. The next day the Japanese captured Jacob Vouza, a retired sergeant major of the protectorate police, who was scouting for Clemens. When they found a small American flag on him, they tied him to a tree, interrogated him, then bayoneted him several times in the chest and neck and left him for dead. Vouza chewed through his bonds, crawled to the American lines and managed to warn the Marines that several hundred Japanese were coming. He survived; for this he later received the American Silver Star and the British George Medal.

Night on Alligator Creek

American reports and official histories named the battle after the Tenaru River, but this was a mapping error: the Tenaru flows a few kilometres further east. The eastern edge of the perimeter was formed by the Ilu River, which the Marines nicknamed Alligator Creek, although the Solomon Islands have crocodiles, not alligators; and the “creek” itself was at this point a stagnant lagoon, separated from the sea by a narrow sandbar. This is why some studies speak of the Battle of Alligator Creek, and Japanese ones of the battle at the Ilu River crossing. On the western bank of the lagoon the 2nd Battalion of Colonel Clifton Cates’s 1st Marine Regiment was dug in. The battalion had machine guns, barbed-wire entanglements and two 37 mm anti-tank guns firing canister, and the divisional artillery had registered on the sandbar and the coconut grove on the far bank.

At about 1.30 a.m. on 21 August a green flare gave the signal to attack. Under cover of machine-gun and mortar fire some hundred Japanese soldiers charged across the sandbar. Most fell to canister and machine-gun bursts, but some managed to cut through the wire and seize a few positions, from which they were driven out only by a counter-attack by the reserve company. An hour later a second wave of 150–200 men went in, and it too was almost entirely wiped out. A few Japanese swam the lagoon and, from an abandoned American amphibian tractor, fired on an anti-tank gun position, killing most of its crew. At about 5 a.m. Ichiki tried to outflank the position by sending men wading through the surf, but this attack too was beaten off by machine-gun and artillery fire. In one of the gun pits by the sandbar three Marines, Corporal Lee Diamond and Privates John Rivers and Al Schmid, fought all night; Rivers was killed, and Schmid was blinded by a grenade blast. An officer who had come back from the second assault advised Ichiki to pull back the survivors, but the colonel refused.

Counter-attack and the end of the detachment

At dawn the American commanders concluded that the remnants of the Japanese were crowded into the coconut grove on the eastern bank of the lagoon. Lieutenant Colonel Leonard Cresswell’s 1st Battalion, 1st Marines crossed the Ilu upstream, swung round in an arc and cut off the enemy’s line of retreat, pushing him towards the sea. Aircraft from Henderson Field, which had arrived on the island only the day before, strafed those fleeing along the beach. In the afternoon a few M3 Stuart light tanks crossed the sandbar and raked the grove with canister and machine-gun fire, crushing the living and the dead under their tracks. The Japanese threw themselves at them with grenades and mines. Vandegrift later wrote that the rear of the tanks “looked like meat grinders”.

At about 5 p.m. resistance ceased. Ichiki was killed in the last phase of the fighting or, according to other accounts, committed suicide after burning the regimental colours; the sources disagree on this point. When the Marines began to walk over the battlefield, wounded Japanese opened fire on them or blew themselves up with grenades together with those who tried to help them. From then on the Marines shot every prone figure that moved. “I have never heard or read of this kind of fighting. These people refuse to surrender,” Vandegrift wrote. Only fifteen or so badly wounded or unconscious men were taken prisoner. According to Japanese figures, 777 men of the detachment were killed and 128 survived, including those who had stayed at Taivu; American estimates speak of about 800 killed. Marine losses are usually given as 44 killed and about 70 wounded.

The survivors made their way back to Taivu and on 25 August reported to Rabaul that the detachment had been “almost completely destroyed at a point some distance from the airfield”. The 17th Army command received the news with disbelief.

Place in the war

The Battle of the Tenaru was small, but of great psychological importance. After eight months of defeats in Malaya, the Philippines and Burma, American soldiers had found that the Japanese infantry, reputed to be invincible in jungle fighting, could be beaten in open combat on land. The battle also revealed what was to characterise the whole Pacific War: Japanese soldiers almost never surrendered, and the wounded fought to the end, which in turn led the Americans to stop taking prisoners. One of those who fought there, Robert Leckie, described the battlefield in his memoirs, and in 2010 the night at the lagoon became the climax of the first episode of the television series The Pacific.

For the Japanese, Ichiki’s defeat was proof that there were more Americans on Guadalcanal than they had believed, but they drew their conclusions only gradually. On 24 August the Imperial fleet, covering Tanaka’s convoy carrying the rest of Ichiki’s regiment, clashed with American carriers in the Battle of the Eastern Solomons, and a day later aircraft from Henderson Field forced the convoy to turn back. From then on reinforcements were brought to the island mainly at night by fast destroyers, the so-called Tokyo Express. In September a brigade under Major General Kiyotake Kawaguchi, several times stronger than Ichiki’s detachment, struck at the airfield and in the Battle of Bloody Ridge came much closer to success. In October a whole division arrived. Yet each successive assault came too late and was too weak for the growing defences, and the air force at Henderson Field, whose first aircraft had flown in on the eve of the battle, remained the Americans’ greatest asset throughout the campaign. Guadalcanal became for both sides a war of attrition on land, at sea and in the air, which lasted until February 1943 and ended with the Japanese evacuation of the island.