20 May, 1961 U.S.A. "Freedom Riders"
1961 : An angry mob consisting of all white's attacked a busload of Freedom Riders (Freedom Riders were testing the United States Supreme Court decision Boynton v. Virginia, that gave them a legal right to disregard local segregation ordinances regarding interstate transportation facilities) in Montgomery, Ala., prompting the federal government to send in United States marshals to restore order.
Taken from: https://www.thepeoplehistory.com/may20th.html