In 1918, the First World War ended with defeat of Germany. In 1919, Britain, France, the United States and oter victor countries held Paris Peace Conderence. As one of victor countries, China also attended the conference. At the conference, China requested that Chinese should take back Shandong province, whose sovereignty was relinquished to Germany before the War. The imperialist powers turned down this request and handed over all claims of Shandong from Germany to Japan and compelled Chinese representatives to sign.

This news caused explosions of outrage in China, and on May 4th, 1919, students of Peking University and other higher instititions gathered in Tiananmen Square to protest, shouting the slogans of "Restore our lost Qingdao Island" and "Down with the traitors". They stormed the house of Cao Rulin and beat someone they met there - Chinese High Commisioner to Japan, Zhang Zongxiang - and then set fire to the house. The Northern government sent troops to suppress students and put over thirty of them under arrest.

On second day, students in Peking University went on strike by going into streets to dis-seminate patriotic ideas. Students from Shandong, Tianjin and Shanghai came to Beijing to support them. The reactionary Northern Warlord government arrested nearly 1,000 students, which caused even greater turbulence all over the country. In June, workers in Shanghai went on strike to support students patriotic requests, to be followed in other cities by students suspending classes, workers downing tools and merchants closing shops. Meanwhile, Chinese delegation to Paris Peace Conference received thousands of telegrams sent by people from all walks of life in China asking them not to sign the treaty. On June 28th, overseas Chinese residents and students in France surrounded the residence of Chinese delegation to urge them not to sign the treaty. Confronted with huge pressure, the Northern Warlord government had to release arrested students and remove pro-treaty ministers Cao Rulin, Zhang Zongxiang and Lu Zongyu from office. Finally, Chinese delegation refused to sign the treaty, which marked the victory of May 4th Movement.

However, the significance of May 4th Movement lay not only in this diplomatic victory. Several years before the movement, new ways of thinking and new culture marked by democracy and science had been spreading rapidly among intellectuals, with Peking University notably as the center. May 4th Movement promoted the combination of Marxism with Chinese Worker's Movement and quickened the setting up of Chinese Communist Party.