Twenty-five people were arrested in Portland, Oregon on Monday after protests gathered in honor of May Day turned violent.  Police say they were forced to revoke demonstration permits after the crowd started throwing rocks, fireworks, and even Molotov cocktails at law enforcement gathered near the rally.

Though May Day originated as a celebration of the transition of the seasons in the Northern Hemisphere, it took an ugly turn in 1886, when socialist and communist groups took to the streets in Chicago on May 1st to call for a uniform eight-hour workday.  After days of mostly peaceful protests and demonstrations, isolated pockets of violence erupted into a full-blown catastrophe on the 4th when law enforcement gathered to disperse the crowd at the completion of the day’s events.  The police captain ordered his officers to stop a short distance from the wagon the final speaker delivered his address from and issued an order to the remaining crowd to disperse peacefully.

At that moment, an explosive tore through the delegation of 180 police officers, killing seven and wounding 60 others.  The remaining officers opened fire in response to the attack, killing a handful of protesters and injuring 200.  The event would become known as the Haymarket Tragedy, and would shape May Day demonstrations for years to come.

Somehow, radical Leftist groups saw this tragedy as a call to arms, and in 1889, the International Socialist Party declared May 1st to be “International Worker’s Day,” in commemoration for the protesters that lost their lives after their group needlessly killed seven police officers tasked with keeping the peace.  Although many would accuse the police of using violence to disperse protests, it was ultimately the socialist protesters themselves that initiated the tragic events of the day.