The Thirty Years? War originated from political sectarian disputes in the Holy Roman Empire, but then became one of the biggest war disasters of modern times, in which many European powers were involved. How the conflict could take on such a destructive dynamic is the question that lies at the heart of the book. As a peace settlement failed to materialise in the Empire, the trouble spots in Europe gradually and unstoppably spread through the Empire. That is how the war entered its devastating escalation phase and finally became a European conflict. The warfare, the composition of the mercenary armies and finally the Peace Congress that ended the war were also European.