Chicago has hosted more national political conventions than any other city. One of the most memorable opened on this date in 1968.

America was deeply divided that year. The war in Vietnam had become unpopular. Martin Luther King and Sen. Robert Kennedy had both been assassinated. Riots had broken out in many cities.

As the Democrats gathered at the International Amphitheatre, thousands of advocates for various causes poured into the city. Mayor Richard J. Daley was determined to ensure orderly demonstrations. The Chicago police and the Illinois National Guard were ready.

The Republicans had already named Richard Nixon as their candidate. The Democrats had two main contenders: Sen. Eugene McCarthy was the anti-war candidate who’d forced President Johnson to retire; Vice President Hubert Humphrey was supported by the party’s old guard.

Humphrey didn’t inspire much enthusiasm, but he had a majority of the delegates behind him. On the convention’s third night he was nominated. Tensions between protesters and cops had been smoldering. Now they ignited.

TV cameras showed violent scenes in Grant Park, where police chased and beat civilians. The protesters claimed the authorities were out of control, that the whole thing was a police riot. The cops and guardsmen said the protesters had refused to obey lawful orders—the mob had become a threat to everyone’s safety, and they feared for their own lives.

Meanwhile, back at the amphitheatre, Sen. Abraham Ribicoff was at the podium talking about the “Gestapo tactics” of Chicago’s police. Mayor Daley was shown on camera shouting an angry response at Ribicoff.

The convention ended the next day. The Democrats left Chicago a badly shattered party, with Humphrey lagging far behind Nixon in the polls. In November the Republicans captured the White House.

Despite the controversy, Daley always defended the actions of his police. “No one was killed,” he reminded the critics. He said he’d received 135,000 messages endorsing his stand, while only 5,000 condemned him.

Yet the image of 1968 remained in the public mind. Chicago would not be the site of another national party convention until 1996.