On May 4, 1886, a bomb exploded during a labor demonstration near Haymarket Square. The ensuing gunfire and chaos brought a grisly end to what began as peaceful support for an eight-hour workday and led to the trial and execution of rally organizers. The incident also drew irrevocable attention to a conversation about workers rights and the role of law enforcement that continues today. In this guide to the key moments and sites of one of Chicago s most confusing and chaotic events, author Joseph Anthony Rulli aims to establish a clearer understanding of its historical significance.