Relying on the special relationship of the Yamamoto family, Yamamoto probably knew the news that the Yue army was about to open up a battlefield in the south, so he took advantage of the fact that the troops stationed in northern Jiangxi had not been transferred, and carried out two large-scale encirclement and suppression operations against Xiao Xiong's anti-enemy special forces in northern Jiangxi, in a vain attempt to wipe out the anti-Japanese forces in the Jiujiang area under his jurisdiction in one fell swoop.

The Ninth Theater Commander's Headquarters reported to the Central Military Commission the summary of the Second Battle of Changsha, especially the intelligence analysis of the Jiangxi Northern Einsatzgruppen. The higher authorities immediately handed over the report to the Technical Research Office of the Kuomintang Military Commission in Yucheng, which was known as the "Chinese Black Room" for its mysterious intelligence department, which specialized in listening and deciphering enemy codes.

Speaking of "China's black room", we have to start with the American Herbert Yadley.

Herbert Yadre was a confidential officer in the U.S. State Department, and after the outbreak of World War I, Adrey created a classified code-breaking unit within the State Department, codenamed "The Black Room", and he is known as the "Father of American Cryptography." He was famous for repeatedly cracking enemy telegraphs in World War I, and Herbert Yardley is known as the father of American ciphers.

In 1938, after Dai Li learned about Yadrey's situation from the telecommunications expert Wei Daming, he secretly contacted Hu Shih, the Chinese ambassador to the United States, and hired Yadre to come to China to help crack the military code on the condition of an annual salary of 10,000 US dollars. In November of that year, under the pseudonym "Robert Osborne", Adrey arrived in Chongqing via Hong Kong.

After the start of the Anti-Japanese War, in order to strengthen the ability to decipher, the military commander established the Telecommunications Technology Research Institute in 1939 in a large house at No. 94 Shenxiandong Street in Yucheng, secretly codenamed "Huolu", directly under the leadership of the Supreme Military Council, and secretly hired Herbert Yadre through the Chinese military attache in the United States.

Dai Li mobilized more than 50 staff members, more than 50 listening machines, and more than 200 listeners to focus on the army's cryptographic system. During his two years of working in China, the "Huolu" intercepted more than 220,000 copies of the army's secret telegrams, focusing on more than 20,000 copies, and achieved considerable results.

At that time, the naval air force often sent planes from Hankou to bomb Yucheng, and the secret telegram group under the Kuomintang Military Command Bureau repeatedly intercepted the cipher telegrams sent by the spies lurking in Yucheng.

Beginning in March 1939, the Yadre group intercepted a large number of telegrams written by the Japanese army in the more complex and difficult to decipher new codes, and before they could report this information upwards, on May 3 and 4, the military planes flew directly from Hankou to Yucheng for two consecutive days, dropping hundreds of bombs. The next day, more than 20 planes attacked Chongqing again. A phenomenon caught Yadre's attention: Why did the Kuomintang air defense units deployed in the Yucheng area not shoot down a few enemy planes? Through the introduction of his Chinese girlfriend Xu Zhen, Yadre became acquainted with a battalion commander of a Kuomintang anti-aircraft artillery regiment stationed in Yucheng, who was nicknamed the "one-armed thief".

After following it closely, Yardre discovered that the new secret message sent by the spy began to contain some English letters. Yardley speculates that the spy uses the method of compiling the "book code", which is an English novel. At this time, the Kuomintang Military Command Bureau provided an important clue: the "one-armed thief" sometimes openly used the radio station of a nearby Sichuan infantry division to exchange secret messages with his "friends" in Shanghai, and he was most likely a Han anniversary. Yadre set his sights on the "one-armed thief".

Yadre and Xu Zhen went to visit the house of the "one-armed thief". Xu Zhen found a novel "The Earth" by the famous American female writer Pearl Race in the study of the "one-armed thief", and the first word on pages 17, 18, and 19 of the book was drawn with a pen. The "one-armed thief" was the eyes and ears of Wang's puppet political axe regime in Yucheng, and he formed a spy network with the German adviser Her Weiner and others in the Nationalist political axe, and secretly told the Japanese bombers to maintain a flight altitude of 3,660 meters to avoid the fire of the Kuomintang anti-aircraft guns with a range of only 3,050 meters. Subsequently, the "one-armed thief" and other internal annihilators were arrested and shot.

In July 1940, Yadre returned to the United States. The pamphlets he left behind that specialized in cryptography techniques such as "translocation" and "substitution" have helped China a lot.

In order to integrate the technical force of code-breaking, in 1940, the Supreme Military Commission explicitly ordered the establishment of the Technical Research Office of the Kuomintang Military Commission. And imitate the name of Yardley's "American Black Room" back then, and call it the "Chinese Black Room".

The military technology room has about 400 to 500 people, and there are six groups under it, and each group is divided into the following groups: The first, second, and third groups are responsible for deciphering the code, the fourth group is responsible for receiving reports, the fifth group is responsible for general affairs, and the sixth group is responsible for deciphering the Chinese code. Of these, four groups have the largest number of personnel. The military technology room is located in the Liujia Garden on the south bank. In order to facilitate the investigation, the fourth group was set up on the high hill opposite Liujia Garden, that is, Rentou Mountain. At that time, the cipher code intercepted by the listening team was mainly sent to Liu's garden on horseback to be deciphered.

In the deserted Huangjuya Rentou Mountain in Nanshan Town, a southern suburb of Chongqing, the sign of "Central Industrial Experimental Research Institute" is hung at the door of a simple building, and the administrative and deciphering organs of the black room are secretly set up here. On the opposite side, two kilometers away, the summit of Rentou Mountain is its password listening office.

There are armed soldiers patrolling a kilometer from Rentou Mountain, and even local villagers are forbidden to enter.

The materials and personnel inside are all through horses, and on the slope of the hillside on the east side of Rentou Mountain, there is a horse farm. There is a house in front of the racecourse, which is the entrance hall for reception, and there is also a diesel engine that generates electricity at the door. There are many big trees on the south mountain, and it is common to see his own plane flying around the mountain, but he himself did not find the houses, people and animals below.

There are no people living within a few hundred meters of Rentou Mountain, and if there is no one to guide you, you will not be able to find this remote and hidden place.

On the mouth of Rentou Mountain, on an open area of nearly 1,000 square meters, there are several rows of houses. Next to the house, there is a basketball court. Go up 50 meters, to the peak of Rentou Mountain, there are more than a dozen irregular holes around the peak, there are half-human tall wild grass outside the cave entrance, it is difficult to find without walking to the edge of the cave. The mountain peak is almost hollowed out, and the tunnels crisscross it, about two meters high, with different widths and unevenness.

There are many radio stations in the tunnels of Rentou Mountain, which can receive and receive telegrams, and can find out in advance when the plane will come to bomb Chongqing.

Any cipher code deciphering agency, listening and deciphering are definitely divided into two places, especially Huang Jueya Rentou Mountain. The entire mountain peak is hollowed out, and several U-shaped tunnels are relatively readable, and in order to achieve mutual confidentiality, each tunnel is a department, each with a different task.

The report of the Ninth Theater Commander's Department soon reached the hands of Chi Buzhou, the chief commissioner of the Kuomintang "Technical Committee of the Military Commission".

Chi Buzhou, born in Minqing County, Fujian Province, went to the University of Tokyo in 1930 for further study, graduated four years later, served in the Military Attache Office of the Chinese Embassy in Yue, and married a girl from Shirahama Eiko.

On July 25, 1937, Chi Buzhou returned to China with his wife and three children, and soon after joined the Second Confidential Unit of the General Affairs Group of the Central Survey and Statistics Bureau of the Kuomintang.

On April 1, 1940, Chi Buzhou entered the Technical Research Office of the Kuomintang Military Commission.

After Chi Buzhou received the telegram from the Ninth War Zone, he felt that this telegram was very important. He immediately organized personnel to analyze a large number of military telegrams intercepted in the recent period.

Recently, the Black Room has made tremendous achievements in cracking the telegrams of the Japanese army.

One day in May 1941, the Nationalist Axe sent this extremely important information that "Nazi Germany decided to start attacking the Soviet Union within about one week around June 20" to Zhou Enlai through Mr. Yu Youren, and Yan'an quickly handed over this important information to the intelligence officers of the Soviet Red Army.

In the early morning of June 21, 1941, the Soviets received the news of the impending German attack from a German deserter, so that the Soviet army knew the news 24 hours before the start of the war, thus avoiding annihilation. And this important information was intercepted and broken by the Black Room.

In May 1941, Chi Buzhou found that the number of telegrams between the Ministry of Foreign Affairs and the Consulate General in Honolulu had suddenly increased dramatically, and the content of the telegrams was always that the Ministry of Foreign Affairs asked the Consulate General in Honolulu to report: the number and names of US warships in Pearl Harbor; the location of the mooring; the time of entry and exit; the timing and pattern of the rest of the U.S. military at Pearl Harbor; Hawaii climate conditions, etc. The Black Room promptly reported this anomalous information to his superiors. Later, the National Political Axe passed the information to the American Political Axe.

One day in mid-November, not long after Chi Buzhou received the report from the Ninth Theater, the "Military Technology Office" deciphered a secret diplomatic telegram that read: The political axe of the former ambassador to Germany is preparing to send his former ambassador to Germany to the United States to carry out the task of "peace talks" in an attempt to form an alliance with the United States. They hastened to report the deciphered telegram to the highest authorities.

The Chinese authorities immediately called US President Franklin D. Roosevelt and demanded that the United States declare war on him, otherwise China would "sell itself." The United States attaches great importance to this, and after consulting with China, Britain, Australia, and other countries, it handed over a memorandum to the political axe. The main conditions set forth in the memorandum were: the withdrawal of all troops from China and Indochina; In China, no political axe or regime other than Chiang Kai-shek's political axe shall be supported; and the abrogation of the treaty of alliance between Ben, Germany, and Italy. Obviously, these conditions in the memorandum could not be accepted by the political axe, and for this reason, the "peace talks" between the United States and the government did not lead to anything in the end.

Then, Chi Buzhou organized the "Military Technology Office" to decipher a "Secret Diplomatic Cable" and found that the political axe was holding business negotiations with the Soviet political axe, and the subject of the negotiations was that the political axe was going to exchange rubber for Soviet timber. It is said that it is a resource-poor country, where do rubber resources come from?

Based on the above information, combined with the large-scale attack on Changsha by the Yue army, and a series of military operations such as Yamamoto's two frantic attacks on the Jiangxi North Special Forces, Chi Buzhou deduced that the reason why the Yue army wanted to take action was that it would soon go south to invade and occupy the rubber-rich Southeast Asian countries.

Therefore, he urgently drafted a report and handed it to the highest authorities, the content of which was that the army was about to move south and prepare to launch a war of aggression against Southeast Asia.