Location
Located on the northern coast of Guadalcanal, to the east of Henderson Field and Lunga. The river in the area was nicknamed 'Aligator Creek' by the Americans, a misnomer, as no alligators inhabit Guadalcanal, only crocodiles.

Battle of the Tenaru ("Battle of the Ilu River or The Battle of Alligator Creek)
The Japanese Army's "Ichiki Regiment" 28th Infantry Regiment, under the command of of Colonel Kiyonao Ichiki, reached the east bank of the Tenaru River, just after midnight on August 21, 1942. 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 Japanese soldiers charged across the sandbar towards the Marines. Marine machine gun fire and 37mm canister rounds 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. 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 Japanese 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.[36] The Marines answered with 75 mm and mortar artillery barrages into the areas east of the creek. 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.[38][39] For the next couple of hours, the two sides exchanged rifle, machine gun, and artillery fire at close range across the sandbar and creek.

At daybreak on August 21, the 1st Battalion, 1st Marine Regiment, under Lieutenant Colonel Lenard 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 light 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 killed during the battle. As curious Marines began to explore the battlefield, some injured Japanese troops shot at them, killing or wounding several Marines. Thereafter, Marines shot or bayoneted all of the Japanese bodies that they encountered, 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.

Ilu River Memorial
White Memorial pillar obscured by high grass, plaque ripped off since 1995. Photo by Peter Flahavin, 1999.

Fighter 3
Emergency airfield to the east of the Ilu River, south of Tenaru village.

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Last Updated
November 11, 2009