The Franco-Prussian War was both unnecessary and imprudent. France initially received all that it demanded from King William of Prussia. Pressure from the legislature and the people of the boulevard, however, then caused French leaders – including Napoleon III – to expand French demands. This allowed Bismarck, the chancellor of Prussia, to manipulate France into declaring a war that he knew Prussia could win. Two characteristics proved fatal for France. First, the French polity and key French leaders succumbed to war hysteria. This allowed emotions to guide their decision-making, rather than rational calculations. Second, an arrogance among French leaders led to military overconfidence and an element of wishful thinking (e.g., about prospective allies). France was, in other words, less powerful than its leaders thought it would be. Finally, the war was imprudent from the French perspective as well. Within two weeks, as a result of French decisions, Napoleon III went into exile, France lost Alsace-Lorraine, a revolt occurred in Paris, and the German states unified.