By the time the First World War ended in 1918, eight million people had died in what had been perhaps the most apocalyptic episode the world had known. This Very Short Introduction provides a concise and insightful history of the 'Great War', focusing on why it happened, how it was fought, and why it had the consequences it did. It examines the state of Europe in 1914 and the outbreak of war; the onset of attrition and crisis; the role of the US; the collapse of Russia; and the weakening and eventual surrender of the Central Powers. Looking at the historical controversies surrounding the causes and conduct of war, Michael Howard also describes how peace was ultimately made, and the potent legacy of resentment left to Germany.