On January 26, 1932, Murai, the consul in Shanghai, issued a "Letter of Mourning" to the Chinese side. The Latin ultimatum is transliterated as "the Book of Lamentation", which means "last word" before negotiations break down. Generally, a State notifies the other party in writing of an issue and accepts its terms within a certain period of time. Otherwise, some kind of coercive measures will be taken, including the use of force, the severance of diplomatic relations, blockades, boycotts, etc.

The Chinese side threatened the Chinese side that if within 48 hours (i.e., before 6 p.m. on January 28), the Chinese side does not agree to the five unreasonable demands put forward by the Chinese side, including "apology", "conviction", "compensation", "banning anti-Japanese activities", and "disbanding anti-Japanese organizations", the Chinese side will take free action.

The so-called freedom of movement of the Chinese side undoubtedly refers to military action. If a conflict breaks out between the two countries in Shanghai, then Weng Zhaoyuan's 78th Brigade and 156th Brigade stationed in Zhabei and other places will bear the brunt.

"The other side has issued an ultimatum to our political axe, threatening us to accede to their rude demands. Now that the situation is extremely grim, all battalions should strengthen their vigilance and try to avoid clashes with Yu himself before the political axe gives a reply, but if Yu himself dares to attack our army station, give me a hard blow! At the beginning of the meeting, Weng Zhaoyuan said menacingly.

"I heard that the political axe has already intended to compromise with the Chinese side, and someone from Nanjing has come to persuade the army commander to let us withdraw the 19th Route Army from Shanghai. As soldiers, we have the responsibility to defend the territory, and even if blood is spilled on the battlefield, we have no complaints. But we were afraid, we didn't die in the hands of the little devils, but fell under the guns of our own people, which will chill the soldiers. As soon as Weng Zhaoyuan's words fell, a lieutenant colonel officer said loudly.

As soon as these words fell, the room immediately fell silent. Weng Zhaoyuan glanced at everyone and said loudly, "Brothers, don't worry, if Shangfeng blames him, I, Weng Zhaoyuan, will bear it alone, and I will never affect you." But if the little devil dares to attack our army's position, you will fight me to the death, if anyone dares to escape, I Weng Zhaoyuan knows you, but the gun in my hand does not know you. ”

"What do you say about the brigade, our 19th Route Army is a leader, and escaping from the battle is not the style of our 19th Route Army. If the little devil dares to come, we will definitely have him back! As soon as Weng Zhaoyuan's words fell, a battalion commander stood up and shouted loudly.

"Travel! What if the political axe really compromises and agrees to the impudent demands of the little devils? Then another man stood up and asked aloud.

"This?" Weng Zhaoyuan was speechless for a while, yes, what should we do if the political axe really agreed to Yuben's rude request and compromised with Yufang? Weng Zhaoyuan also asked himself the same question in his heart, whether to disobey the order and resist, or obey the orders of the political axe, Weng Zhaoyuan was also very entangled in his heart.

At this time, Jin Zhao suddenly stood up and said, "Don't worry, even if the political axe compromises with the Yue Fang, the little devil will not give up." The dozens of warships and thousands of marines of the little devils are not here for a beach vacation. Even if the political axe compromises with the little devil, the battle of Shanghai is inevitable, because of the ambition of the little devil wolf, the concession of the political axe will never be able to satisfy their greedy appetite, and our top priority now is to step up preparations for war. ”

Sure enough, in the face of the unreasonable demands and ultimatums put forward by the Japanese side, Shanghai Mayor Wu Tiecheng adhered to the principle of Lao Chiang's instructions of "bearing the burden of humiliation" and immediately sent police to shut down the "Shanghai Anti-Japanese Salvation Association" and other anti-Japanese organizations, and sought a compromise with the anti-Japanese army by attacking the anti-Japanese patriotic forces. At the same time, in order to prevent the 19th Route Army from disobeying the order, Lao Chiang secretly ordered Zhu Peide, chief of staff, and He Yingqin, minister of military affairs, to immediately send the 6th Military Police Regiment from Nanjing to Shanghai, and deploy it in the middle of the combat units of the two armies to play a buffering role, so as to prevent unforeseen incidents.

Originally, Cai Tingkai instructed Weng Zhaoyuan's troops to refuse to hand over the defense of the Zhabei area on the grounds that the situation was tense, the war was imminent, and the 19th Route Army had the responsibility to defend the territory. However, a number of bigwigs in Nanjing sent telegrams instructing the 19th Route Army to exercise restraint, claiming that the current state warlords were in a state of internal strife, military orders and government orders were not uniform, and financial constraints were unable to start an all-out war with Yueben, so they tried their best to avoid conflict and advocated forbearance. After learning of the attitude of the political axe, Jiang Cai and others were frustrated, but finally reluctantly said that they would obey the military order and withdraw from Shanghai. Jiang Guangnai said: "Follow the orders of the political axe." ”

On the afternoon of 27 January, Zhu Peide, chief of staff, and He Yingqin, minister of military affairs, transferred the 6th Regiment of the Military Police to take over the defense of the 19th Route Army in the Zhabei area of Shanghai. The regiment boarded the train at Nanjing Station at 8 p.m. on the 27th and arrived at Zhenru at noon on the 28th, and its first battalion arrived at Shanghai North Railway Station in the afternoon to prepare to take over the defense of the 6th Regiment of the 156th Brigade of the 78th Division of the 19th Route Army at dawn on the 29th.

At the request of the Nanjing political axe and various circles in Shanghai, Shanghai Mayor Wu Tiecheng replied to Murajing at 13:45 on the 28th, accepting all the unreasonable demands put forward by the Chinese side.

In the afternoon of the same day, Jin Zhao came to the brigade headquarters again and persuaded the brigade commander Weng Zhaoyuan to strengthen his vigilance. "Think about it, the little devils are a group of jackals, no matter how we compromise and retreat, we can't satisfy the appetite of the little devils, because their ultimate goal is to destroy our Huaxia. Speculation is that tomorrow at the latest, maybe just tonight, the little devil will make a move. Please give the order immediately to prevent accidents. Jin Zhao spat and said to Weng Zhaoyuan.

At this time, Weng Zhaoyuan already knew that the political axe had agreed to the rude request of the Yue Fang, and also received the order to change the guard issued by the military department, Weng Zhaoyuan had already begun to arrange the troops to change the guard, but after listening to Jin Zhao's words, he couldn't help but hesitate, although he had doubts about Jin Zhao's words, but Weng Zhaoyuan, who was cautious in his surname, still accepted Jin Zhao's suggestion and ordered the troops to strengthen their vigilance.

At this time, that is, on the afternoon of the 28th, the cruiser "Yubari" of the Momoto Navy led the 22nd, 23rd, and 30th destroyers, a total of 12 destroyers, carrying more than 460 men of the 2nd Special Marine Corps, to Shanghai. At the same time, the Ministry of the Navy ordered the transfer of aircraft carriers "Kaga" and "Hosho," three cruisers "Naka," "Yura," and "Abukuma," and four mine ships to Shanghai from the mainland.

Rear Admiral Koichi Shiozawa, commander of the 1st Foreign Fleet and commander of the Special Marine Corps stationed in Shanghai, threw the telegram into the trash can without even looking at it, and ordered the troops to proceed as planned. At this point, war was inevitable.