The Defiance Campaign was launched on 26 June 1952, the date that became the yearly National Day of Protest and Mourning. The South African police were alerted about the action and were armed and prepared. In major South African cities, people and organizations performed acts of defiance and civil disobedience. The protests were largely non-violent on the parts of the participants, many of whom wore tri-color armbands signifying the ANC. Black volunteers burned their pass books. Other black volunteers would go into places that were considered "whites-only," which was now against the law. These volunteers were arrested, with the most arrests (over 2,000 people) being made in October 1952. When protesters were arrested, they would not defend themselves in court, "leading to large-scale imprisonment." Others who were offered fines as an alternative chose to go to prison. The mass imprisonment, it was hoped, would overwhelm the government.