Answer:
To protest against the Vietnam war, and political unrest
Step-by-step explanation:
The antiwar protesters gather outside the convention to protest against the Vietnam war which has lasted for 13 years at the time, and the political status quo at the time, which has involved the assassination of Martin Luther King Jr in April 1968 and the Presidential aspirant Kennedy.
The protesters which was led by the Youth International Party (yippies) and the National Mobilization Committee to End the War in Vietnam (MOBE).
The protest occurred in Chicago in 1968 at the Democratic National Convention.