Further moratoria were undertaken on 18 September 1970 and again on 30 June 1971. Arguably, the peace movement had lost its original spirit, as the political debate degenerated, according to author Paul Ham, towards "menace and violence". Dominated by elements Ham identifies as "left-wing extremists", the organisers of the events extended invitations to members of the North Vietnamese government to attend, although this was prevented due to a refusal by the Australian government to grant them visas. Attendance at the subsequent marches was lower than that of May 1970, and as a result of several factors including confusion over the rules regarding what the protesters were allowed to do, aggressive police tactics, and agitation from protesters, the second march became violent. In Sydney, 173 people were arrested, while in Melbourne the police attempted to control the crowd with a baton-charge.