Truman National Security Project

August 19, 1942: Guadalcanal: The Battle of The Tenaru River


Caught by surprise when the Marines invaded Guadalcanal two weeks prior, the battle at the Tenaru River was the Japanese Army’s first attempt to re-capture Henderson Field and drive the Marines off the island. Despite the gritty and determined Marine defense of Wake Island, the Japanese Army continued to underestimate the Marine Corps fighting ability; after all did the Americans not choose the humiliation of surrender rather than a warrior’s death at Bataan and Corregidor?

The Japanese Forces:

Commanded by Col Kiyono Ichiki, the Japanese sent 900 soldiers to reinforce their existing forces and drive the Marines off Guadalcanal. He was a military man; tall and precise, and decided it was not necessary to bring his 1,100 remaining troops. Named after its commanding officer, the Ichiki Detachment had prior combat experience in China, and early reports on the American troops said “when they were pressed for time, the American positions and especially their organization of fire are not coordinated.” Ichiki decided to attack before the Marines got themselves coordinated.

The Marines:

Ichiki was wrong; the Marines were already coordinated. Shortly after noon on August 18, a patrol from 2nd Battalion, 1st Marines discovered and attacked a large party of Ichiki’s laying communications wire. Discovering four senior officers and accurate maps of the Marine positions among the 31 now-dead Japanese, the Marine commander, LtCol Al Pollack, spent the afternoon moving the majority of his riflemen, machine guns, and a 37mm anti-tank weapon behind a single strand of barbed wired they strung across a sandspit on the Tenaru River. Later that evening, SgtMaj Jacob Vouzo of the Solomon Island Police escaped from the Japanese and told Pollack there were perhaps 500 Japanese troops massing across the river to attack.

The Fight:

On 19 August at 0118 the Ichiki attachment attacked into the strength of the Marine defense. Held up by that single strand of barbed wire, they hacked at it with their bayonets as the waiting Marines opened fire. Using their machine guns, Springfield rifles, and hand grenades, the Marines cut huge holes in the Japanese who attacked directly into the Marine 37mm anti-tank weapon. The 37 mm was firing canister shot that cut down entire squads at a time – and as its barrel glowed red in the darkness, the Ichiki’s charged again and again and finally broke through the barbed wire.

Screaming “Marine you die” they were into the Marine lines and in what would become the standard of ferocity in the Pacific, the Marines and Japanese fought hand-to-hand. But as Pollack fed his reserve platoon into the fight, the cries of “Banzai” faded under the non-stop hammering of the Marine machine guns and the incessant ‘wham’ of the anti-tank gun. See: Pvt Al Schmid; In His Own Words

By morning, more than 700 dead Japanese were counted at the cost of 34 Marines killed and 75 wounded, with the Japanese commander, Col Ichiki burning his colors and shooting himself in the head. The report radioed to Tokyo said “The attack of the Ichiki Detachment was not entirely successful.”

Andrew Lubin is a Contributing Writer for the Truman Doctrine. Views expressed are his own.. This article originally appeared in’s Military section.