Relief map of Karafuto

Karafuto was the Japanese-controlled southern half of Sakhalin Island, just north of Hokkaido. The major port was Otomari. The territory was awarded to Japan by the Treaty of Portsmouth in 1905, and a flood of Japanese immigrants soon overwhelmed the 1300 indigenous Ainu. The territory was supervised by the Ministry of Colonial Affairs until late 1942, when the latter was absorbed into the new created Greater East Asia Ministry and Karafuto became an integral part of the Japanese home islands. The governor-general held high bureaucratic rank (chokunin) but was not usually a military officer.

The valley of the Tym' and Poronai Rivers forms the chief communication corridor between north and south, and the Japanese placed most of their defenses here, around the town of Koton (Pobedino; 142.828E 49.843N). By August 1945, the defense consisted of 88 Division, with 125 Regiment manning the fortified zone around Koton and the remainder of the division dispersed through Karafuto. The Koton Fortified Region was 7.5 miles (12 km) wide and up to 10 miles (16 km) deep. The defenses were organized into a security zone 1.5-2 miles (2-3 km) deep backed by a security belt 5 miles (8 km) further back. Fortifications in the security belt included two reinforced concrete pillboxes, four earth and timber pillboxes, and 22 concrete embrasures and extensive barbed wire and antitank obstacles. Behind the security belt was the main line of resistance, with over one hundred pillboxes and bunkers. A final defensive belt, though with few fortifications, lay to the rear of the main line of resistance. The total defending force was 5400 men with 42 heavy machine guns, 94 light  machine guns, 28 guns and mortars, and 27 grenade launchers.

On 11 August 1945, the Russians launched a major attack on Karafuto from northern Sakhalin. 1 Far East Front intended to use Karafuto as a springboard for an invasion of Hokkaido, but the attacking 56 Rifle Corps met furious resistance at the Honda strong point and was unable to break the main Japanese defensive belt until 18 August. The Japanese conducted a fighting withdrawal and could not be overcome before 3 September 1945, even after 113 Rifle Regiment was landed at Maoka (Kholmsk; 142.058E 47.045N) on 16 August to flank the Japanese. The combination of fanatical resistance from the Japanese and diplomatic pressure from Truman, based on provisions of the Potsdam agreement placing Hokkaido within the American occupation zone, prevented Russian occupation of Hokkaido.

Frank (1999)

Glantz (2003)

Myers and Peattie (1984)

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