On 28 June 1914 Archduke Franz Ferdinand, heir to the Austrian throne, was murdered in Sarajevo in Bosnia, which had been annexed by Austria in 1908. The assassin and his co-conspirators were members of a Serbian nationalist group called ‘the Black Hand’. In less than five weeks the alliance systems of the great powers had turned this local incident into a European war. The origins of the First World War are a source of major historical controversy that has refused to disappear over the years. The historiographical debate must, therefore, inform any discussion about the events that ‘triggered’ a European and then a world war in 1914.