On May 21st, more than a million people in Hong Kong took to the streets to support the democracy movement; this accounted for one-sixth of Hong Kong's total population, making it the largest march in the past 20 years. March organizer Lee Cheuk-yan later recalled, "As the main director, I knew there would be a lot of participants, but when I saw one million Hong Kong people taking to the streets, I couldn't never have imagined. After 4 hours of waiting [at the march site], we still couldn't get started, because people just kept coming. Hong Kong people had never expressed their feelings for their country like this." The newspaper "Wen Wei Po" described the scene as "a glorious day that will be inscribed forever in the history of Hong Kong, and the most important symbol of the Hong Kong people's awakening since the founding of the city".

At the end of the march, the Joint Committee on the Promotion of Democratic Government (JCPDG) announced the establishment of the Hong Kong Alliance in Support of Patriotic Democratic Movements of China (The Alliance). At the same time, the JCPDG passed a declaration "calling on all Hong Kong people to join the Alliance immediately to fight for the democracy movement in China and contribute to the future of democracy in China; calling on the People's Liberation Army and the Armed Police not to conduct a crackdown on Beijing students, the National People's Congress to immediately call an emergency meeting to remove Li Peng from office, and the immediate withdrawal of the military from Beijing."

The Alliance was officially registered after the June 4th crackdown, on June 15th. Its first directors consisted of 20 people, including Szeto Wah, Martin Lee Chu-ming, Chong Yiu-kwong, Father Louis (Keloon) Ha, Cheng Kai-nam (Gary Cheng), Cheung Man-kwong, Albert Ho (Ho Chun-yan), Lee Cheuk-yan, and Chu Yiu-ming. The purpose of the organization was to support the democracy movement in China, and to support Chinese democracy activists and student organizations. Over the next few decades, the Alliance continued to influence the development of social movements in Hong Kong, and to build up forms of resistance for the Hong Kong people.

References: "The Big Bang of History: A Complete Record of the June 4th Incident"; "The Tiananmen Papers"; [眾新聞("Citizen News")(Chinese)] (https://www.hkcnews.com/article/20657/六四30周年-1989年百萬港人上街-支聯會-20675/【六四30周年】百萬港人不分黨派上街-「團結感覺非常強」); BBC中文網("BBC News Chinese Edition")(Chinese)