Starting in 1845, a fungus spread throughout the Irish potato crop, destroying the harvest and causing mass starvation and disease. Poverty-stricken peasants flocked to the cities, where conditions were not much better and disease spread easily. An estimated one million people died as a result of the potato blight, and an equal number emigrated out of Ireland.
Fire destroyed a large proportion of the city of Chicago in 1871. Mary Harris's home and business were destroyed.
On May 1, 1886, an anarchist demonstration turned violent when one of the participants threw a bomb at policemen, who responded by opening fire. Many innocent people died, and the authorities saw this as an opportunity to arrest and convict prominent activists. With little evidence, the activists were sentenced to be executed and imprisoned. Despite international protest, four of the activists were hanged. Later, the remaining imprisoned activists were pardoned.