Students Occupy Admin Lounge at University of Nanterre, Paris

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An action involving 150 students, including Daniel Cohn-Bendit, took over the 8th floor administrative lounge at the University of Nanterre, in Paris, France on March 22nd, 1968.  

The move to occupy the space was motivated to protest the arrest of six students who had been implicated in vandalism of the American Express office during a protest against the Vietnam War on March 20th.

The occupation at Nanterre was ended when the Dean brought in the metropolitan police to remove the students.  In the public scuffle that ensued, media attention was raised and this event became a flash-point in the series of actions that eventually snowballed into the "barricades" and the protests throughout France in May 1968.

Later, this incident at Nanterre became known as The Movement of 22nd March.

Sources:

Wikipedia.