Hu Yaobang

It had been set off by the death of the reformist leader Hu Yaobang - and it ended with a bloody military crackdown that killed hundreds or, by some estimates, thousands.

The death of a leader in China can usher in big changes, it did after Mao Zedong, or can lead to political upheaval, like it did when grieving for Hu Yaobang morphed into the 1989 Tiananmen Square protests.

Studying law at Peking University, he was the campus secretary of the ruling party’s Communist Youth League, an organization that launched the political careers of former party leaders Hu Jintao and Hu Yaobang.

But it was the death of Hu Yaobang, a party leader who pushed for democratic reforms before his forced resignation, that sparked mass gatherings across the country.

The passing of Premier Zhou Enlai in 1976 and General Secretary Hu Yaobang in 1989 both fueled student-led protests and calls for deeper reform.