The final weeks of World War I saw a revolutionary upheaval in Europe, as old empires collapsed and new, self-proclaimed 'nation-states' emerged in their place. For its advocates, the Yugoslav state created in 1918 represented a largely uniform culture and identity. But as its official name - the Kingdom of the Serbs, Croats and Slovenes - suggested, its population was by no means homogeneous. Too late, the British - who had been instrumental in...