The war began in 1618 with a revolt of Protestant Bohemia against the Catholic Habsburg Empire. After Bohemia's defeat in 1620, the war spread into western and southern Germany. In subsequent years, Spain (1621), Denmark (1626), Sweden (1630), and France (1635) became involved. Historians generally are not explicit on why the war began and then spread throughout Europe; they are mostly divided between those who believe it was a German war that was joined by other powers and those who believe it was an international war simply triggered by events in the Habsburg Empire. The Thirty Years War was a Central European war that came to involve so much of the continent because the Habsburg Empire was so extensive. | The war began in 1618 with a revolt of Protestant Bohemia against the Catholic Habsburg Empire. After Bohemia's defeat in 1620, the war spread into western and southern Germany. In subsequent years, Spain (1621), Denmark (1626), Sweden (1630), and France (1635) became involved. Historians generally are not explicit on why the war began and then spread throughout Europe; they are mostly divided between those who believe it was a German war that was joined by other powers and those who believe it was an international war simply triggered by events in the Habsburg Empire. The Thirty Years War was a Central European war that came to involve so much of the continent because the Habsburg Empire was so extensive. |