June 4, 1989 is an anniversary the Chinese government wants its people to forget.

Sparked by the mid-April death of Hu Yaobang, a former general secretary of the Chinese Communist Party, students started gathering in Tiananmen Square in the days that followed. Hu was seen as a reformer by students and soft on “bourgeois liberalism” by party leaders, threatened by his call for term limits.

The student protests set in motion another force the regime truly feared, China’s working class — which is why Deng Xiaoping, the paramount leader after Mao’s death in 1976, was willing to use deadly force to stop the struggle in its tracks. This fear is still apparent today, as the Chinese state has gone to — and continues to go to — great lengths to erase this history from memory.