The moments that it took Gavrilo Princip to step forward to the stalled car and shoot dead Franz Ferdinand and his wife were perhaps the most fateful of the modern era. An act of terrorism of staggering efficiency, it fulfilled its every aim: it would liberate Bosnia from Habsburg rule and it created a powerful new Serbia, but it also brought down four great empires, killed millions of men and destroyed a civilization. The terrible sequence of events that this unleashed are well known, but much less clear and contentious are the factors which made a seemingly prosperous and complacent Europe so vulnerable to the impact of this assassination. In The Sleepwalkers Christopher Clark retells the story of the outbreak of the First World War and its causes. Drawing on many fresh new sources, this account reveals a Europe very different from the familiar picture, putting Serbia and the Balkans at the centre of the story. Starting with the brutal assassination of Alexander I of Serbia in 1903, Clark shows how, far from being the place of enviable stability it appears to us, Europe was racked by chronic problems: a multipolar, fractured, multicultural world of clashing ideals, terrorism, militancy and instability, which was, fatefully, saddled with a conspicuously ineffectual set of political leaders. He shows how the rulers of Europe, who prided themselves on their modernity and rationalism, behaved like sleepwalkers, stumbling through crisis after crisis and finally convincing themselves that war was the only answer. The Sleepwalkers re-imagines the First World War to make it feel raw and in many ways modern. Above all, it shows how there was a total failure to understand the seriousness of the chaotic, near genocidal fighting in the Balkans: it was this failure that would drag Europe into catastrophe.