Chicago police fired on striking workers
When Chicago police fired on workers during a general strike for the eight hour day, killing several demonstrators and resulting in the deaths of several police officers, largely from friendly fire. May Day was formally recognized as an annual event in 1891.
Where was the Maguindanao massacre on 23 November 2009, when 58 victims, including a politician's wife, his two sisters, journalists, lawyers, aides, and motorists who were witnesses, were kidnapped and brutally killed?
What is the name for the massacre of the French ruling class while in church by local people at Palermo in 1282 that started a revolution that spread to other parts of the country?