Hyakutake took command of the Seventeenth Army at Rabaul on 18 May 1942. His new command consisted of scattered infantry regimental groups in that area. Hyakutake was to work with the navy to establish new airfields and positions in New Guinea, the Solomon Islands, and points east. The Japanese canceled their seaborne attack on Port Moresby after the Battle of the Coral Sea. Instead, in July 1942, Hyakutake ordered Major General Horii Tomitaro to advance overland with his South Seas Detachment in New Guinea to capture Port Moresby.
Hyakutake's attention was diverted to the Solomons when U.S. Marines landed on Guadalcanal on 7 August 1942. Hyakutake underestimated both the number and fighting abilities of the Americans, and he continued to feed in units on a piecemeal basis. When Major General Kawaguchi Kiyotake's 6,000 men came to grief on Bloody Ridge on Guadalcanal during 13–14 September, Hyakutake at last realized his error and put a hold on further operations on New Guinea.
Hyakutake then built up a force of 30,000 men on Guadalcanal and left Rabaul on 8 October to take personal command. His overly complicated military plan involved separate columns intended to concentrate near American positions. This offensive opened on 24 October. Despite the bravery of the attackers, superior U.S. firepower drove off the Japanese with heavy losses.
By early November, the Japanese on Guadalcanal were desperately short of supplies. The Japanese then reorganized their command in the South Pacific. General Imamura Hitoshi took command of the new Eighth Area Army. Hyakutake's forces in the Solomons remained the Seventeenth Army; those on New Guinea were renamed the Eighteenth Army. Although Imamura promised Hyakutake two fresh divisions, he was unable to deliver on this promise because the Japanese navy was unable to control the sea around Guadalcanal.
After Imperial General Headquarters decided to evacuate Guadalcanal, in February 1943 Hyakutake took command of the garrison on Bougainville. The Americans invaded that island on 1 November 1943, forcing Hyakutake's men into defensive positions, especially around Buin. To support that isolated garrison, Hyakutake spent much time organizing vegetable gardens. His attempt to break out during 8–24 March 1944 was unsuccessful. Imamura then ordered Hyakutake to adopt a live-and-let-live attitude toward the Americans.
Hyakutake's remaining forces on Bougainville surrendered at the end of the war. Hyakutake himself had been disabled by a stroke in early 1945. He returned to Japan in February 1946 and died at Hiratsuka on 10 March 1947.
Tim J. Watts
Frank, Richard B. Guadalcanal. New York: Random House, 1990.; Hayashi, Saburo. Kogun: The Japanese Army in the Pacific War. Westport, CT: Greenwood Press, 1959.; Morison, Samuel Eliot. The Struggle for Guadalcanal: August 1942–February 1943. Boston: Little, Brown, 1949.