The Battle of the Tenaru was a land battle between the Imperial Japanese Army and Allied forces on August 21, 1942, at Guadalcanal in the Solomon Islands during World War II. The U.S. Marines were defending the Lunga perimeter around Henderson Field, which had been captured by the Allies on August 7. The Japanese unit, commanded by Kiyonao Ichiki (pictured), was sent to recapture the airfield and drive the Allied forces off the island. Underestimating the strength of the Allied forces, Ichiki's unit conducted a nighttime frontal assault on Marine positions at Alligator Creek on the east side of the perimeter and were defeated with heavy losses. The Marines counterattacked after daybreak, and about 800 of Ichiki's original 917 men were killed. After Tenaru, the Japanese realized that Allied forces on Guadalcanal were much greater in number than originally estimated and sent larger forces for their later attempts to retake Henderson Field. (This article is part of a featured topic: Guadalcanal Campaign.)