The First World War shaped the twentieth century. It sparked the Russian Revolution and launched America as a world power. The fault-line from its failed peace settlement led to a second terrible world war barely twenty years later. We live with its unresolved consequences; in the Middle East, the Balkans and Ireland. It began as a clash in the Balkans which grew to engulf Europe and the world. Britain joined in, more to protect her great empire than for the defence of small nations. The merciless pattern of the war was set early on, by Austro-Hungarian atrocities against Serbian civilians.