Riots erupted in April 1968 as a reaction to?

... the Democratic National Convention. The city of Chicago was inundated with "hippies" who were politically active young adults of the time. They were resistant to laws, police, and the status quo. The "hippies" had unconventional ways of expressing their opinions, primarily in support of Senator McCarthy. For example, to express their opposition to Chicago Police, the hippies would drop baggies of feces from hotel Windows on to officers below. When Senator McCarthy appeared in Grant Park to speak to his supporters, however, he was surrounded by a protective detail of Chicago Police officers (in plan clothes). When the convention activities eventually got out of hand, Mayor Richard J. Daley gave his famous order to the police, "shoot to kill."