Why did a riot break out at the Democratic National Convention in 1968?

During the Democratic National Convention in 1968, a riot broke out. They were anti-war protesters who wanted to demonstrate that they were against the Vietnam War being carried out at that time. This group of protesters gathered the same day of the Democratic National Convention to show their dissatisfaction towards the war. There was conflict with the police on the streets. It was a time of violence, political turbulence, and civil unrest.

1) Police responded violently to the protestors.

3) Protestors became aggressive in expressing their views.

4) Protestors were angry about the war in Vietnam.