On August 28, 1968, at the Democratic National Convention in Chicago, thousands of Vietnam War protesters battle police in the streets, while the Democratic Party falls apart over an internal disagreement concerning its stance on Vietnam. Over the course of 24 hours, the predominant American line of thought on the Cold War with the Soviet Union was shattered.

Since the end of World War II, the U.S. perspective on the Soviet Union and Soviet-style communism was marked by truculent disapproval. Intent on stopping the spread of communism, the United States developed a policy by which it would intervene in the affairs of countries it deemed susceptible to communist influence. In the early 1960s, this policy led to U.S. involvement in the controversial Vietnam War, during which the United States attempted to keep South Vietnam from falling under the control of communist North Vietnam, at a cost of more than 2 million Vietnamese and nearly 58,000 American lives.

The “Cold War consensus,” in U.S. government, however, fractured during the Democratic National Convention in Chicago in 1968. Democratic delegates from across the country were split on the question of Vietnam. A faction led by Eugene McCarthy, a committed anti-war candidate, began to challenge the long-held assumption that the United States should remain in the war. As the debate intensified, fights broke out on the convention floor, and delegates and reporters were beaten and knocked to the ground. Eventually, the delegates on the side of the status quo, championed by then-Vice President Hubert Humphrey, won out, but the events of the convention had seriously weakened the party, which went on to lose the following election.

Meanwhile, on the streets of Chicago, several thousand anti-war protesters gathered to show their support for McCarthy and the U.S. withdrawal of troops from Vietnam. Chicago Mayor Richard Daley deployed 12,000 police officers and called in another 15,000 state and federal officers to contain the protesters. The situation then rapidly spiraled out of control, with the policemen severely beating and gassing the demonstrators, as well as newsmen and doctors who had come to help.

The ensuing riot, known as the “Battle of Michigan Avenue,” was caught on television, and sparked a large-scale change in American society. For the first time, many Americans came out in virulent opposition to the Vietnam War, which they had begun to feel was pointless and wrongheaded. No longer would people give the national government unrestrained power to pursue its Cold War policies at the expense of the safety of U.S. citizens.