There, in the early summer of the year 1630, landed King Gustavus Adolphus of the house of Vasa, king of Sweden, and famous as the man who had defended his country against the Russians. A Protestant prince of unlimited ambition, desirous of making Sweden the centre of a great Northern Empire, Gustavus Adolphus was welcomed by the Protestant princes of Europe as the saviour of the Lutheran cause. He defeated Tilly, who had just successfully butchered the Protestant inhabitants of Magdeburg. Then his troops began their great march through the heart of Germany in an attempt to reach the Habsburg possessions in Italy. Threatened in the rear by the Catholics, Gustavus suddenly veered around and defeated the main Habsburg army in the battle of Lützen. Unfortunately the Swedish king was killed when he strayed away from his troops. But the Habsburg power had been broken. Ferdinand, who was a suspicious sort of person, at once began to distrust his own servants. Wallenstein, his commander-in-chief, was murdered at his instigation. When the Catholic Bourbons, who ruled France and hated their Habsburg rivals, heard of this, they joined the Protestant Swedes. The armies of Louis XIII invaded the eastern part of Germany, and Turenne and Condé added their fame to that of Baner and Weimar, the Swedish generals, by murdering, pillaging and burning Habsburg property. This brought great fame and riches to the Swedes and caused the Danes to become envious. The Protestant Danes thereupon declared war upon the Protestant Swedes who were the allies of the Catholic French, whose political leader, the Cardinal de Richelieu, had just deprived the Huguenots (or French Protestants) of those rights of public worship which the Edict of Nantes of the year 1598 had guaranteed them. The war, after the habit of such encounters, did not decide anything, when it came to an end with the treaty of Westphalia in 1648. The Catholic powers remained Catholic and the Protestant powers stayed faithful to the doctrines of Luther and Calvin and Zwingli. The Swiss and Dutch Protestants were recognised as independent republics. France kept the cities of Metz and Toul and Verdun and a part of Alsace. The Holy Roman Empire continued to exist as a sort of scare-crow state, without men, without money, without hope and without courage. [Illustration: AMSTERDAM IN 1648]