At the diet of Augsburgh, in 1530, the Protestant princes of Germany delivered to the emperor their Confession of Faith; they afterwards, at Smalcald, entered into an offensive and defensive league against the emperor. Being sensible that they were unable to resist him, they engaged the French monarch in their cause. At first, the emperor was victorious; but a new league was formed. France then took a more active part in favour of the confederates, and the contest ended in the peace of Passau, in 1552, there the two parties, for the first time, treated as equals, and the free exercise of the Lutheran religion was allowed. Things remained quiet during the reigns of Ferdinand the First and Maximilian the Second; but, in consequence of the disputes, which arose on the succession to the dutchies of Cleves and Juliers, the religious differences broke out with fresh animosity:--the Protestant princes formed a confederacy called the _Evangelical Union_, and placed, at its head, the Elector Palatine; the Catholics formed a confederacy called the _Catholic League_, and placed, at its head, the Duke of Bavaria. In the year 1618, they burst into open war; every state in Europe, and even the Ottoman princes, at one time or other, took a part in it. France was the soul of the Protestant cause; she assisted it with her armies, and her subsidies:--it may be truly said, that, if there be a Protestant state from the Vistula to the Rhine, or a Mahometan, state between the Danube and the Mediterranean, its existence is owing to the Bourbon monarchs. From the period of its duration, it has been called the WAR OF THIRTY YEARS: it is divided, by its _Palatine, Danish, Swedish,_ and _French_ periods. [Sidenote: CHAP. XI. 1634-1645.] 1. Frederick, the fifth _Elector Palatine_ of that name, being elected King of Bohemia, by the states of that kingdom, made war on the emperor Ferdinand the Second. Being defeated in 1620, at the battle of Prague, and abandoned by his allies, he was driven from Bohemia, and deprived of his other states. 2. Christian the Fourth of _Denmark_, then placed himself at the head of the confederacy against the emperor; but, having in 1626, lost the battle of Lutter, in which Tilly commanded the Austrian forces; he signed, three years after that event, a separate peace with the emperor. In the following year, Gustavus Adolphus, King of Sweden, was placed at the head of the confederacy. Their cause appeared desperate: Walstein, the Austrian general, had been uniformly successful, and almost the whole of Germany had submitted to the emperor: but the Austrians soon experienced a severe reverse of fortune. [Sidenote: Embassy of Grotius to the Court of France.]