The long uphill battle for workers' rights in the United States experienced one of its most shocking and bloody episodes on the dark Chicago night of May 4, 1886.
Chicago was a somewhat labor-friendly city compared to its eastern counterparts, and as such had become a refuge for laborers run out of eastern towns for attempting to organize.
Chicago was also home to a large population of immigrant German laborers who had a rich history of guild labor.
These factors made Chicago the epicenter of the 8-Hour-Day Movement which was gaining momentum in 1886.
On May 1, 1886, a large and multi-day organized labor demonstration began with 80,000 workers marching up Chicago's Michigan Avenue arm-in-arm, waving the banners of their unions and singing sings.
Iron Workers made up the single largest trade group within the 80,000.
Tragically, the peaceful event took a violent turn on May 3, when police attacked and killed picketers at the McCormick Reaper Plant.
The attack provoked the planning of an evening rally for the following day, May 4th, to be held at Haymarket Square. However, in its haste, this gathering was poorly planned and suffered from low turnout and poor coordination.
The Mayor of Chicago, Carter Harrison, made an appearance and--hoping to preserve the fragile piece--commanded the police to leave.
As soon as the Mayor left, however, chaos ensued.
The small group of about 200 laborers was attacked by 176 armed policemen.
And then, in a blast that would be heard 'round the industrial world, someone threw a dynamite bomb into the crowd.
It was the first use of such an explosive during peacetime in the history of the world.
When the smoke settled and the gunfire stopped, at least four workers and seven policemen had died.
No police officers were held accountable for their actions, and the following year four of the laborers arrested that night were hanged for the crime of anarchy.
Cries for justice for the abused laborers of the Haymarket Affair would help lead the growth of the newly founded American Federation of Labor, and the arduous journey for proper labor rights in the United States plodded on.