The Molly Maguires was a secret Irish Catholic society, originally bent on terrorizing English mine and landowners in the name of labor justice. At the center of labor strikes and violence from the time of the society’s arrival in the United States in the 1850s, the Molly Maguires came to be associated in the minds of most Americans with lawlessness and vigilante justice.
The Mollies were an American model of the Ancient Order of Hibernians, which had revolted against English landowners in Ireland. According to legend, an Irish woman named Molly Maguire had murdered local landowners and agents in retribution for their oppression of the common people, thus attracting a passionate following among the oppressed. In the United States, the Molly Maguires used arson and murder throughout the coal mining regions of eastern Pennsylvania during the 1860s and 1870s in order to intimidate mine supervisors. They became so powerful in some places that they held official positions within municipal governments and police forces. After infiltration by an agent of the Pinkerton Detective Agency in 1875, the movement was effectively destroyed by 1877 with the arrest and execution of most of the Molly Maguire leaders.