The Poznań protests of 1956 (Poznański Czerwiec) were several massive protests against the communist government of the Polish People’s Republic.

In June 1956 demonstrations by workers demanding better working conditions at Poznań’s Cegielski Factories were met with violent repression. An estimated 100+ people were killed and hundreds more sustained injuries.

The Poznań protests were an important milestone on the way to the Polish October and the installation of a government with less Soviet control.

Source: Wikipedia