the basis of the same issues animating the Reformation, however. Thirty Years' War: 1618–1648 The Reformation and Counter-Reformation era conflicts are termed the European wars of religion. In particular, the Thirty Years' War (1618–1648) devastated much of Germany, killing between 25% and 40% of its entire population. The Catholic House of Habsburg and its allies fought against the Protestant princes of Germany, supported at various times by Denmark, Sweden and France. The Habsburgs, who ruled Spain, Austria, the Crown of Bohemia, Hungary, Slovene Lands, the Spanish Netherlands and much of Germany and Italy, were staunch defenders of the Catholic Church. Some historians believe that the era of the Reformation came to a close when Catholic France allied itself with Protestant states against the Habsburg dynasty. Two main tenets of the Peace of Westphalia, which ended the Thirty Years' War, were: All parties would now recognise the Peace of Augsburg of 1555, by which each prince would have the right to determine the religion of his own state, the options being Catholicism, Lutheranism, and now Calvinism (the principle of ). Christians living in principalities where their denomination was not the established church were guaranteed the right to practice their faith in public during allotted hours and in private at their will. The treaty also effectively ended the Papacy's pan-European political power. Pope Innocent X declared the treaty "null, void, invalid, iniquitous, unjust, damnable, reprobate, inane, empty of meaning and effect for all times" in his apostolic brief Zelo Domus Dei. European sovereigns, Catholic and Protestant alike, ignored his verdict. Consequences of the Reformation Six princes of the Holy Roman Empire and rulers of fourteen Imperial Free Cities, who issued a protest (or dissent) against the edict of the Diet of Speyer (1529), were the first individuals to be called Protestants. The edict reversed concessions made to the Lutherans with the approval of Holy Roman Emperor Charles V three years earlier. The term Protestant, though initially purely political in nature, later acquired a broader sense, referring to a member of any Western church which subscribed to the main Protestant principles. Today, Protestantism constitutes the second-largest form of Christianity (after Catholicism), with a total of 800 million to 1 billion adherents worldwide or about 37% of all Christians. Protestants have developed their own culture, with major contributions in education, the humanities and sciences, the political and social order, the economy and the arts