Zhongma Fortress Zhongma Fortress , or Unit Tōgō , was a biological warfare research facility erected by the Japanese Kwantung Army in Beiyinhe , outside of Harbin , Manchukuo during the Second Sino - Japanese War . Background . Shirō Ishii , an Imperial Japanese Army senior researcher in biological and chemical warfare , was assigned to establish a clandestine program to develop weapons of mass destruction under the patronage of Army Minister Sadao Araki . Ishii built a medical research facility in Harbin shortly after the city came under Japanese control after the Manchurian Incident in 1932 . This facility conducted legitimate medical research on vaccine s and public health . However , the facility was too close to a highly populated area to be able to conduct clandestine biological warfare research , so Ishii selected a second site about 100 kilometers to the south of Harbin at the village of Beiyinhe . The local inhabitants were forcibly evacuated and their village burnt down , and a large tract of land was fenced off . Description . The new facility had three metre high earthen walls topped with electrified barbed wire and a moat with drawbridge surrounded the buildings within . There were hundreds of rooms and smaller surrounding laboratories , office buildings , barracks and dining facilities , warehouses and munitions storage , crematoria , and the prison cell s . Out of necessity , the Japanese were forced to use local Chinese labor for the construction ; but due to secrecy , laborers had to wear a basket over their head to prevent them from seeing more than small sections of the facility , and had be escorted by the army guards . The prisoners brought to Zhongma included common criminals , captured bandits , anti - Japanese partisans , as well as political prisoners and people rounded up at random for suspicious behavior by the Kempeitai . Human experimentation . A variety of bizarre medical experiments were conducted on the prisoners at Zhongma Fortress . Prisoners were usually well fed , on their usual diet of rice or wheat , with meat , fish and occasionally even alcohol – with the intent of starting experiments with the subjects in their usual state of health . In many cases , prisoners were drained of blood over several days , with careful records kept on their deteriorating physical condition . Others were subject to experiments on or water deprivation . Prisoners who survived the experiments , but who were deemed too weak for further tests were executed . The facility was estimated to have held between 500 - 600 prisoners at any one time , with a capacity for over 1000 . Closure . In August 1934 , at the time of the traditional summer festival , the prisoners were given a ration of special foods . One prisoner , named Li , managed to overpower his guard , seize the keys and free about forty of his fellow prisoners . Although their legs were shackled , their arms were free , and the prisoners were able to climb the outside walls . A heavy downpour had knocked out the facility ' s electricity , deactivating the searchlights and electric fence . Some ten of the escapees were shot by guards ; others were recaptured or died of exposure , but several managed to escape , and spread word of the crimes against humanity being conducted by Shiro and his subordinates . As a result of this publicity , Zhongma Fortress was closed down , and its activities transferred to a new site closer to Harbin called Pingfang ( Heibo ) , which came to be known as Unit 731 . The testimony of one of the escapees , Ziyang Wang , was collected by Xiao Han , deputy director of the Pingfang museum , in the 1980s . The graphic novel " Maruta 454 " ( 2010 ) , by Paul - Yanic Laquerre , Song Yang and Pastor , depicts the escape of 12 Chinese prisoners from Unit Tōgō , based on Wang ' s testimony .