In December 1940, Kawaguchi was promoted to major general and took command of the 35th Infantry Brigade. On the outbreak of the Pacific war, his unit took part in amphibious operations resulting in the capture of Borneo (December 1941), Cebu (March 1942), and Mindanao (April 1942). In late August 1942, he landed on Guadalcanal from Rabaul, in charge of some 3,500 reinforcements. He then commanded some 6,000 troops in their efforts to retake Henderson Field. His men participated in the 13–14 September Battle of Bloody Ridge, taking heavy casualties during their attempt to penetrate the U.S. defensive perimeter. Prior to another major Japanese attack on 24–25 October 1942, Kawaguchi opposed Seventeenth Army commander Lieutenant General Hyakutake Haruyoshi's plan for a frontal assault, arguing for a flanking movement instead. On the day of the assault, Hyakutake removed Kawaguchi from his command and dismissed him.
Kawaguchi returned to Japan and was attached to the headquarters of the Eastern District Army. In March 1943, he was relegated to the unassigned list and the next month the reserve list. Kawaguchi remained there until March 1945, when he was reactivated as commander of the Tsushima Island Fortress Zone. In February 1946, he was arrested on war crimes charges for the execution of the Philippines minister of justice. Tried and convicted, he was sentenced to imprisonment at hard labor and was incarcerated from 1946 to 1953. Kawaguchi died in Tokyo on 16 May 1961. Asakawa Michio
Frank, Richard B. Guadalcanal: The Definitive Account of the Landmark Battle. New York: Penguin, 1990.; Griffith, Samuel B. The Battle of Guadalcanal. Philadelphia: Lippincott, 1979.