Double Tenth Incident The " Double Tenth Incident " or " Double Tenth Massacre " occurred on 10 October 1943 , during the Second World War Japanese occupation of Singapore . The " Kempeitai " – Japanese Military Police – arrested and tortured fifty - seven civilians and civilian internees on suspicion of their involvement in a raid on Singapore Harbour that had been carried out by Anglo – Australian commandos from " Operation Jaywick " . Seven Japanese ships were sunk , but none of those arrested and tortured had participated in the raid , nor had any knowledge of it . Fifteen of them died in Singapore ' s Changi Prison . After the war ended , twenty - one of the " Kempeitai " involved were charged with war crimes . Eight received the death sentence , seven were acquitted , and the remainder were given prison sentences varying from one year to life . History . In 1943 , a special branch of the " Kempeitai " under Lieutenant Colonel Haruzo Sumida was charged with finding the culprits responsible for acts of sabotage in Singapore , mainly the cutting of telephone lines and the burning of warehouses . Sumida strongly suspected that the saboteurs were being organised by internees in Changi Prison , and made preparations for a raid on the prison to catch the ringleaders . Sumida ' s chief suspect was British barrister Rob Heeley Scott , a prominent Foreign Office employee who had previously been detained for his anti - Japanese propaganda , released by the " Kempeitai " , and then later sent to Changi Prison . However , neither Scott nor anyone else in Changi was involved in the sabotage , or with the raid that led to serious repercussions on 10 October – ' The double tenth ' . On 28 September , Scott received a message from one of his contacts in the city , telling him that on the previous morning six Japanese ships had been blown up in Singapore Harbour ( now Keppel Harbour ) . This was the first major sabotage since the Japanese had captured the island . The loss of ships in such an important place was an enormous blow to Japanese prestige . Scott and his fellow internees supposed that the saboteurs must have been Chinese guerrillas who had slipped across the straits from their base in Malaya . Sumida , however , believed that Scott and his associates had planned the operation from Changi Prison . " Operation Jaywick " . The attack on Singapore Harbour was codenamed " Operation Jaywick " , the brand name of a popular lavatory deodoriser , and had nothing to do with guerrillas or fifth columnist s . It had been carried out by Lieutenant Colonel Ivan Lyon from ' Z ' Special Unit , a group of Anglo – Australian commandos who had sailed from Western Australia to Singapore in an old Japanese fishing boat , the " Krait " , named after a Malayan snake . Once within striking distance of the harbour , the commandos took to folboats ( folding canoes ) , and paddled into the docks under cover of night . Using limpet mines , they sank six Japanese ships of 2 , 000 – 5 , 000 tons , including several tankers , and then slipped away to their rendezvous with the " Krait " , finally returning successfully to Australia . ( The " Krait " is now preserved and on display at the Australian National Maritime Museum in Sydney ) . The Japanese could not conceive that a force could penetrate their lines of defence and have the audacity to attack their shipping . They therefore concluded that it must have been an internal operation , carried out by Chinese guerrillas organised from Changi Prison . Arrests and torture . On the day before the " Double Tenth " , internees were ordered to parade in the open at nine o ' clock the next morning . No explanation was given . When the parade had assembled , the camp commandant came out with a number of " Kempeitai " and troops , who closed all the exits . While the names of a few men were called out for immediate arrest , the " Kempeitai " conducted a thorough search of the entire prison . After incriminating evidence including diaries of war news compiled from the BBC ' s radio broadcasts , self - made radios , and a tin box containing a substantial amount of money belonging to an ex - banker were unearthed , several more arrests were made , mostly of people who had been involved in monitoring news broadcasts and running a secret information service throughout the prison . This started a period of terror that lasted for several months . Suspects were hauled from their homes and places of work . Internees were taken to the " Kempeitai " interrogation chambers , where they were subjected to torture and starvation to make them confess to acts of sabotage and treason . As none of the suspects had even heard of " Operation Jaywick " , let alone been part of it , any confessions they made were meaningless , lacking any information about the raid itself , how it had been organised , or where the explosives had been obtained . Elizabeth Choy . Elizabeth Choy and her husband , Choy Khun Heng , were running their canteen at the Tan Tock Seng Hospital , after all the patients and doctors had been moved from the Miyako Hospital ( former Woodbridge Hospital ) . She had been a school teacher in St Andrew ' s School before the war . The couple helped the Changi prisoners - of - war ( POW ) by passing on cash and parcels containing such things as fresh clothing , medicine and letters during their deliveries . An informant told the " Kempeitai " that the Choys were involved in smuggling money into Changi Prison , and Khun Heng was arrested . After several days , Elizabeth went to the YMCA on Stamford Road , used by the " Kempeitai " as their headquarters , known as the Kempeitai East District Branch , to inquire about her husband . The Japanese denied all knowledge of him , but three weeks later they lured her back to the YMCA and confined her with other Chinese and Changi prisoners . There was no sign of Khun Heng . The prisoners were forbidden to speak to one another , although one of the internees , John Dunlop , secretly taught them to communicate in sign language . At Elizabeth ' s first interrogation session , the Japanese told her that some ships had been sunk in the harbour and they wanted to know the location of a large amount of money . She claimed no knowledge of the matter but was repeatedly interrogated and beaten . At various times , the Kempeitai forced Elizabeth to kneel on some angled bars of wood on the floor . They stripped her topless and tied her to the wood so she could not go either forwards or backwards . Then they applied electric shocks to her . They even brought in her husband to let him see her being tortured . After nine months in captivity , Elizabeth had lost half her body weight . Innocent victims . Seven days after the Double Tenth , Bishop John Wilson of St Andrew ' s Cathedral was taken to the YMCA , and placed in the cell next to Elizabeth . He was severely beaten for three days before the Japanese accepted that he was not one of the ringleaders in their imagined conspiracy . One night Elizabeth saw Rob Scott , by then badly disfigured as a result of the beatings and water tortures that he had been subjected to . At the end of one session Scott was told that he had been sentenced to death , and was forced to write a farewell letter to his wife . He was later sentenced to six years ' imprisonment in Outram Road Prison instead , the site where convicted sepoy mutineers had been detained and executed by the British Army in 1915 . Elizabeth was held in the YMCA for nearly 200 days , during which time the " Kempeitai " meticulously followed up every point in her story , cross - examining people she said she had helped . After a huge dossier of interviews had been compiled , the Japanese concluded that she was telling the truth and set her free . Khun Heng , however , was sentenced to 12 years in Outram Road Prison . People avoided Elizabeth following her release , too terrified to speak to her . Fifteen internees died in the " Kempeitai " ' s cells during the Double Tenth inquisition . The suffering spread to the entire civilian population of Changi Prison ; rations were cut , and games , concerts , plays , and school lessons were forbidden for months . The ' double tenth ' trial . After the war , on 18 March 1946 , the ' double tenth ' war crimes trial was held in the Supreme Court Building , before a military court presided over by Lieutenant Colonel S . C . Silkin . Twenty - one " Kempeitai " were accused of torturing 57 internees , resulting in the deaths of 15 . On 15 April 1946 , after a hearing lasting 21 days , Sumida was one of eight sentenced to death by hanging . Three others received life imprisonment , one a sentence of fifteen years , and two were given prison terms of eight years . Seven were acquitted . In recognition of her valour and wartime effort during the Japanese Occupation , Elizabeth Choy was awarded in London the Order of the British Empire ( OBE ) in 1946 .