On December 2, 1941, a young Chinese intelligence officer in a cramped room in Chongqing decoded a message from Japan's Foreign Ministry to its ambassador in Washington: 'Burn all secret codes and secret documents and move the embassy's deposits to the bank of a neutral country: the imperial government has decided at the highest level to take action.' Knowing the cables that had gone before, the officer concluded that Japan was about to attack the United States five days later at Pearl Harbour. He passed the information to his superior, who gave it to president Chiang Kai-shek. Chiang sent an urgent cable to the US embassy; its diplomats judged that the Kuomintang did not have the technology to crack Japan's secret codes and threw the cable into the rubbish bin. The officer, Chi Buzhou, was the master code-breaker of China's intelligence during the second world war. On April 13, 1943, he decoded a cable from the headquarters of the Imperial Japanese Army saying that Isoroku Yamamoto, commander of the Combined Fleet and the man who led the attack on Pearl Harbour, would be flying from Rabaul to Ballale airfield, in the Solomon Islands, on the morning of April 18. This time the Americans believed him and sent a squadron of fighter aircraft to intercept the Mitsubishi aircraft with Yamamoto on board and the six escorting Zero fighters. Yamamoto's plane crashed into the jungle. The death of their most famous admiral was a major psychological blow to the Japanese public, who were only told of the event on May 21. Chi is one of the most important unsung heroes of China's war effort. Only now is he achieving the recognition he deserves thanks to a popular television series, Feng Yu, based on his life. The series aired on China Central Television's national Channel Eight last month and reached a peak of No 2 in the ratings. Now CCTV is selling it to city and provincial cable stations. Before the series, few Chinese had ever heard of him, in part because he worked for the Kuomintang government and in part because of the secrecy surrounding what he did. His personal story is worthy of a Shakespeare play. Chi was born in 1908 into a large peasant family in Minqing, in rural Fujian province. His family was so poor that he did not go to school until he was 10, with financial assistance from one of his older brothers. An outstanding student, he completed primary school in three years and went to study at one of the best middle schools in the provincial capital, Fuzhou . In 1927, he earned a place at Tokyo Imperial University, the most famous institute of higher learning in Japan, where he finished a degree in electrical engineering. Then he did a degree in industrial studies at Waseda and met and married the love of his life, Akiko Shirohama. Chi took a part-time job at the Chinese embassy in Tokyo and, introduced by a fellow student, joined the Kuomintang. He wrote nearly 20 articles for a magazine published by Chinese students in Japan. In July 1937, the Japanese military launched its attack at the Marco Polo bridge outside Beijing. 'I felt that an all-out war between China and Japan was imminent and that, as a Chinese, I could not go on living there and decided to return home at once,' he wrote in his memoirs, completed in 1986. Shirohama's family told her to choose between them and her husband from the 'enemy country': she chose Chi and her family cut her off. With their three children, they boarded a ship in Kobe on July 25, 1937. The police boarded the ship and detained them on the pier. Only when a Japanese friend came to vouch for them and paid fees demanded by the police were they able to reboard, minutes before the ship left for Shanghai. After arrival, they went to the capital, Nanjing (then Nanking), where they found everyone frantically preparing to escape the arrival of the Japanese. Chi found a guest house for students who had returned from Japan. 'There was immediately a Japanese air raid and no bomb shelter. The five of us hid under a bed with a cotton blanket.' A fellow returnee from Japan invited Chi to join a counter-intelligence unit set up to break Japanese military and civil codes. 'I told him that, in Japan, I had studied electrical engineering and economics. I knew nothing about codes. But he quoted President Chiang as saying that a person who could break secret codes was like adding an army of over 100,000 troops. I was very moved. I was young and patriotic and agreed. It was an extremely difficult mission, to master something of which I had no knowledge.' The unit had been set up in Chongqing, the wartime capital, by an American cryptologist, Herbert Yardley, who had founded MI-8, a US military intelligence unit, in June 1917. In 1931, Yardley wrote a book, The American Black Chamber, about his experiences, which became a best-seller around the world. President Chiang liked the book so much that he offered Yardley an annual salary of US$10,000 to set up a similar unit in China. In November 1938, he arrived in Chongqing, set up a team to crack Japanese codes and recruited more than 30 Chinese who had studied in Japan, including Chi. Chi was very strong in mathematics and, with an excellent memory, was able to remember figures. He made his first breakthrough in March 1939, when he read a cable from the Japanese Foreign Ministry to its offices around the world. The chief of staff was delighted and put Chi in charge of a team of 45 people. They broke codes that detailed plans to bomb Chongqing. 'We threw ourselves into the task,' Chi recalled later. 'For us, there was no day or night. We had to succeed in our mission. We were exhausted but it was a joyful kind of exhaustion, with a great sense of achievement.' Chi found that the code was a mixture of English letters, Japanese writing and numbers, with two letters denoting a Chinese or Japanese character. He worked out, for example, the letters to denote units of the Chinese army, the number of soldiers and the quantity of ammunition. (west wind tense) meant that relations with the US were bad: (clear in the north) meant that relations with the Soviet Union were improving. On a boat from Hong Kong to Haiphong, Yardley met a man who introduced himself as a 'German Jewish engineer' and said he was going to Chongqing 'because he liked the food'. Yardley was suspicious and sent an agent to the man's hotel to spy on him. One evening, the 'engineer' sent messages by telegraph. He was arrested and confessed that he was a Japanese agent preparing for a team of special forces to parachute in and kidnap or assassinate Chiang. Yardley stayed in Chongqing until March 1940, when poor health and revelations in The New York Times forced him to return home. In April 1940, Chiang set up 'the Chinese black chamber', with 500 operatives divided into six units, with the mission of breaking Japanese military and diplomatic codes. It later broadened its task to reading the secret messages of the Communist Party, the competing factions in the KMT and the British, American and Soviet missions in China. From May 1941, Chi found a sudden heavy increase in cable traffic between Tokyo and its consulate in Hawaii, including requests for information on the numbers and position of naval vessels in Pearl Harbour, when they went out for manoeuvres, which was the rest day - Sunday - and the weather situation. It was these cables, plus the one on December 2 calling for the burning of the codes and documents at the Washington embassy, that caused him to predict, correctly, the attack on Sunday, the seventh. In October 1942, he decoded an order to send a Japanese air squadron to leave a base in Burma and bomb Calcutta. This was passed to British air command in New Delhi, enabling it to intercept and destroy the squadron. That month, Chi also discovered a Japanese plan to shoot down a plane carrying Sun Ke, the son of Sun Yat-sen. He managed to reach Sun at Chongqing airport just as he was about to board. He turned back - but the plane continued on its journey and was shot down; all those on board were killed. In October 1943, Chi was transferred to another division of the army to provide training and was promoted to the rank of major. After the civil war between the Nationalists and Communists broke out, he did not want to take part and took his family to his hometown in Fujian. He later took a job in a bank in Shanghai. He decided against following the KMT government to Taiwan. We threw ourselves into the task. For us, there was no day or night.