On April 24, 1919, Liang Qichao sent a telegram from Paris to the National Diplomatic Association: "Regarding the issue with Germany, I have heard that it will be directly handed over to Japan regarding Qingdao, as the Japanese envoy strongly insisted and Britain and France were moved. If we accept this, it would be like tying ourselves up with ropes. Please warn the government and the people, and strictly urge all plenipotentiaries (representatives) not to sign, to show our determination."
From April 29 to 30, representatives of Britain, the United States, and France attending the Paris Peace Conference held a meeting, with the Japanese representative invited to attend. They decided on the provisions concerning the Shandong issue in the Treaty of Versailles (Articles 156, 157, and 158), transferring the rights and interests that Germany had seized in Shandong to Japan.
On May 1, Chinese negotiators and Foreign Minister Lu Zhengxiang informed the Beijing government by telegraph about this matter, stating that if they did not sign the treaty, it would be detrimental to the abolition of extraterritorial rights, the cancellation of the Boxer Indemnity, tariff autonomy, and compensation for losses. The Beijing Government's Foreign Affairs Committee (an advisory body of the Presidential Office) convened an emergency meeting and decided not to sign the treaty. The "Beijing Correspondence" of the Da Lu Bao newspaper revealed: "The government received a message from the Chinese delegation in Paris stating that the diplomatic struggle to recover the Jiaozhou Concession has already failed."
On May 2, the Beijing government secretly notified the Chinese representatives in Paris that they could sign the treaty. Lin Changmin, the secretary-general of the Foreign Affairs Committee, wrote articles in the Morning Post and the National Gazette, calling out: "Shandong is lost, the country is doomed. I hope all four hundred million people will fight with their lives." Peking University President Cai Yuanpei informed the students of the failure of the diplomacy.
On May 3, the people of Beijing urgently discussed strategies. That night, students of Peking University held a student meeting at the auditorium of the Law School, inviting representatives from 13 secondary and higher schools in Beijing. The meeting decided to hold a demonstration on May 4 (Sunday) at Tiananmen Square.
At 10 am on May 4, student representatives from various schools met at the Special School of Law and Politics to determine the route of the demonstration. Some students who prepared to take violent action wrote farewell letters. At 1 pm, more than 3,000 students in Beijing gathered at Tiananmen Square from all directions, with the Peking University students hanging a blood-stained "Return Our Qingdao" poster at the scene. After a brief gathering and speech, the group marched toward the embassy district. When reaching the western gate of Dongjiaominxiang, they were blocked by police. Students then elected representatives to request meetings with the envoys of four countries. Only the U.S. embassy staff accepted the students' petition, while the British, French, and Italian embassies refused to accept it, citing that the envoys were not present. More than 3,000 students stood under the scorching sun for two hours. Seeing that the embassy district could not be passed through, they became even more enraged and turned towards Cao Ruyun's residence at Zhaojiacou. As they marched, they gave speeches, and "many people saw them crying, many Westerners took off their hats and cheered, and some police also cried." (Weekly Review, May 11, 1919). Around 4 pm, the students arrived at Cao's residence. Kuang Husheng, a student from the Department of Mathematics and Physics of Beijing Normal University, jumped into the house first and opened the door, allowing the student group to enter. They beat the Japanese envoy Zhang Zongxiang who was in the house at that time. Unable to find Cao Ruyun, the students, in anger, set fire to his house around 4:30 pm. Later, the military police arrived, arrested the students, and a total of 32 students were arrested.
On May 5, major universities in Beijing went on strike. Students from Tsinghua University, who were outside the city and did not participate in the action on the 4th, announced: "Starting today, we will act in unison with other schools."