On September 2 1989 anti-apartheid protesters marching on Parliament were stopped by police near this spot. They mounted an impromptu sit-in and police retaliated with tear gas, batons and a new weapon: a water cannon laced with purple dye to stain demonstrators and make them easier to identify and detain. As protesters scattered, one climbed onto the armoured vehicle with the cannon and turned the purple jet on police. Purple dye stained most of the surrounding buildings, including the National Party headquarters and the white-washed walls of the historic Old Townhouse. The next day graffiti all over the city proclaimed "The Purple Shall Govern". This was one of the last protest marches outlawed by the apartheid government. Eleven days later, 30 000 people marched through the city without police intervention.