As the battle on the ridge took place , Kawaguchi 's Kuma and Oka units also attacked the Marine defenses on the east and west sides of the Lunga perimeter . The Kuma battalion — led by Major Takeshi Mizuno — attacked the southeastern sector of the Lunga perimeter , defended by Marines of the 3rd Battalion , 1st Marine Regiment ( 3 / 1 ) . Mizuno 's attack started around midnight , with one company attacking through Marine artillery fire and engaging in hand @-@ to @-@ hand combat with the Marine defenders before being thrown back . Mizuno was killed in the attack . After daybreak , the Marines , believing that the rest of Mizuno 's battalion was still in the area , sent forward six light tanks without infantry support to sweep the area in front of the Marine lines ; four Japanese 37 mm ( 1 @.@ 46 in ) anti @-@ tank guns destroyed or disabled three of them . After abandoning their burning tanks , several of the disabled tanks ' crewmembers were bayoneted and killed by the Japanese . One tank tumbled down an embankment into the Tenaru River , drowning its crew .