In 1931 and 1932, New South Wales faced civic collapse. During the last months of the Lang government, the semi-fascist New Guard became a serious threat to the state. This article examines the challenge posed by the New Guard to the New South Wales police, and the strategies used by the police to suppress the group. Superintendent W.J. MacKay, the colourful and Machiavellian future commissioner, effectively and ruthlessly exercised police power against the New Guard. This article disputes the dominant historical interpretation of this period, which sees the police as collaborators with a reactionary secret army, the ‘Old Guard’. This article has been peer-reviewed.