Four-straight nights of savage violence in Northern Ireland have reminded the international community that despite the Good Friday Agreement and the years of painful progress that followed, there are still serious dangers that lurk in Ulster. The violence reminds both Catholics and Protestants that a small minority can still destabilise the delicate work done by the majority in both communities.

Last week's violence was triggered by a decision to allow a Protestant parade to pass through a mainly Catholic neighbourhood on July 12. It is sad that Protestants need to insist on their rights to march to celebrate the victory, over 300 years ago, of England's Protestant King William III over his ousted Catholic predecessor, James II, in 1689. The marchers are well aware that their actions are designed to inflame the interfaith rivalry. The slogans they shout, the songs they sing and the banners they carry are all about Protestant victory over the Catholics.

It is specious for them to claim that marching is a key to their communal and cultural identity. There are many Protestant communities in the world that do not march to define their identity. The marches in Ulster are about defining an ancient enmity, which should now be forgotten.