Pinkerton massacre of Homestead strikers: "In 1892, the Homestead Strike was an industrial lockout and strike between Pittsburgh, Pennsylvania steel workers, and the Carnegie steel company, who hired armed Pinkertons to act as strike-breakers. It culminated in a battle between strikers and private security agents on July 6, 1892.[3] The battle was one of the most serious disputes in U.S. labor history, third behind the Ludlow Massacre and the Battle of Blair Mountain. After the thousands of rioters forced the encircled pinkertons to surrender, the US sent in national guard troops to suppress the strike, killing ~9 and arresting hundreds. 1"