A World at War: What Started It and What Did It Change?

Imagine a room full of people who all distrust each other. Each one is secretly armed, and they have all made promises to defend their friends if anyone is attacked. Then someone fires a single shot. Suddenly, everyone is fighting — even people who had no quarrel at the start. This is almost exactly what happened in Europe in 1914. Before you read on, think about this: when something violent happens, is one person always to blame? Or can a situation build up over years until almost any spark sets it off?