April 17, 1989: Tens of thousands of university students gathered in Tiananmen Square, Beijing, calling for press freedom and other pro-democracy reforms

June 3 and 4, 1989: Chinese government troops fired on the crowd, killing an untold number of people

June 5, 1989: An unarmed man, known only as “Tank Man,” stood his ground before a column of tanks on the Avenue of Eternal Peace, Beijing

Source: PBS.org