Hatred of a common foe - first and foremost Feyenoord – fosters an abiding camaraderie. And sometimes violence erupts. At the ‘battle of Beverwijk’ in 1997, someone was actually killed. For years, mayors of Amsterdam and Rotterdam ban rival supporters from their city’s stadiums. With CCTV cameras watching their every move, these days the fans confine themselves to verbal abuse: Feyenoord fans are cockroaches and harbourslaves; Ajax fans are Jews and noses.