The was an infantry division of the Imperial Japanese Army. Its call sign was the . It was formed on 24 August 1937 in Kanazawa as a square division, simultaneously with the 108th division. The nucleus for the formation was the 9th division headquarters. It was subordinated from the beginning to the Japanese Northern China Area Army. First formation The 109th Division was sent to North China in October 1937. It closely cooperated with the 108th division, contributing to the Beiping–Hankou Railway Operation and the capture of the Linfen city. Later it also provided a garrison for the Shanxi province. The division was eventually dissolved 24 December 1939. Second formation The 109th Division was reformed in May 1944 from the 1st Independent Mixed Brigade and other Bonin Islands garrisons reinforced by recruits from the Kōfu mobilization district. The 109th Division was assigned to the 31st Army, under Commanding Lieutenant General Hideyoshi Obata. It comprised the bulk of the Japanese garrison on the volcanic islands of Iwo Jima and Chichi Jima which were wiped out by American forces from February to March 1945 in Battle of Iwo Jima. The structure of the 109th was different than most divisions in the IJA. After 1936, the normal make up of a division was the triangular organization, with three infantry regiments to a division. The 109th (along with the 91st Infantry Division) were considered square divisions because they had two infantry brigades (5000 men each) with two infantry regiments each. During the buildup prior to the attack of Iwo-jima General Kuribayashi divided the 109th and each was built up to maximum strengths. The 109th, as the Ogasawara island Detachment was the Ogasawara (Bonin Islands) District Group, also called the Ogasawara Army Group, with an approximate strength of 47,000 troops. 1st Brigade The 1st Independent Mixed Brigade, led by Major General Tachibana, and the 17th Independent Mixed Regiment, as well as other elements, were stationed on Chichi Jima (Father Island) with approximately 25,000 troops. Many were deployed to other island defenses such as the rest of the middle cluster known as Father Island (groups); Ani-jima, Ototo-jima, Mago-jima, along with islets Higashi-jima, Nishi-jima, and Minami-jima. The northernmost cluster or Groom Islands (group) included; Yome-jima, Muko-jima, and Nakōdo-jima or Nakadachi-jima. The southernmost cluster known as the Mother Island (group) of Haha-jima, Ane-jima, Imōto-jima, Mei-jima, along with the smaller Hira-shima and Muko-jima. These groups of islands were by-passed