In the 1840s, Philadelphia is dubbed the “Workshop of the World.” Irish and German people — mostly Catholic — immigrate to work in the booming city. Nativists are spreading a false rumor that Catholics are trying to remove the Bible from public schools.

On May 6, 1844, a fight breaks out between Irish Catholics and attendees of a nativist rally composed mostly of Protestants. For three days, mobs attack immigrant neighborhoods with clubs, guns and torches. A sheriff gathers a posse, but they are unable to quell the rioting until a militia arrives. At least fourteen are killed, scores injured, dozens of homes and buildings and two Catholic churches are burned to the ground.

In two months, riots resume, this time involving cannon fire. In reaction, the city establishes the Philadelphia Police Department.