The Tiananmen Square Incident of April 5, 1976, which was a protest against the Gang of Four following the death of Zhou Enlai; also refers to the 四五运动 sì​wǔ​yùn​dòng

The student-led demonstrations and subsequent military crackdown in 1989; also known as the 六四事件 liù​sì​shì​jiàn or 六四惨案 liù​sì​cǎn'àn