the Japanese prisoner of war system, which treated captives with extreme brutality. Many of the abuses were documented in Japanese war crimes trials, such as those committed by the Kempeitai East District Branch in Singapore, including the Sook Ching. The Kenpeitai also carried out revenge attacks against prisoners and civilians. For example, after Colonel Doolittle's raid on Tokyo in 1942, it carried out reprisals against thousands of Chinese civilians and captured airmen, and in 1943 committed the Double Tenth massacre in response to an Allied raid on Singapore Harbour. The Kenpeitai also supplied 600 men, women and children per year to the infamous Unit 731, which conducted human experimentation. Organization The Kenpeitai was divided into three branches: the Keimu Han (police and security), Naikin Han (Administration), and Tokumu Han (Special Duties). The Kenpeitai's General Affairs Branch was in charge of the force's policy, personnel management, internal discipline, as well as communication with the Ministries of the Admiralty, Interior, and Justice. The Operations Branch was in charge of the distribution of military police units within the army, general public security, and intelligence. The Kenpeitai maintained a headquarters in each relevant Area Army, commanded by a Shosho (Major General), with a Taisa (Colonel) as Executive Officer. The headquarters comprised two or three field offices, each staffed with approximately 375 personnel and commanded by a Chusa (Lieutenant Colonel), with a Shosa (Major) as Executive Officer. The field offices in turn were divided into 65-man sections called 'buntai', each commanded by a Tai-i (Captain), with a Chu-i (First Lieutenant) as Executive Officer. The buntai were further divided into 20-man detachments called bunkentai, commanded by a Sho-i (Second Lieutenant), with a Junshikan (Warrant Officer) as Executive Officer. Keeping with the main organizational structure of the Kenpeitai, each of these detachments contained a police and security squad, an administration squad, and a special duties squad. Kenpeitai Auxiliary units consisting of regional ethnic forces were organized in occupied areas. These troops supplemented the Kenpeitai and were considered part of the organization, but were limited to the rank of Socho (Sergeant Major). By 1937, the Kenpeitai had 315 officers and 6,000 enlisted personnel as part of its official forces. The Allies estimated there were at least 7,500 Kenpeitai members by the end of World War II. Active units The Kenpeitai operated commands on the Japanese mainland and throughout all occupied and captured overseas territories during the Pacific War.