Bartholomew Sastrow was born at Greifswald, a prosperous Hanseatic town, in 1520. The year of his birth is famous in the history of German Protestantism, for it witnessed the publication of Luther's three great Reformation tracts--the _Appeal to the Christian Nobility of the German Nation_, the _Babylonish Captivity_, and the _Freedom of a Christian Man_. It seemed in that year as if the whole of Germany might be brought to make common cause against the Pope. The clergy, the nobility, the towns, the peasants all had their separate cause of quarrel with the old régime, and to each of these classes in turn Luther addressed his powerful appeal. For a moment puritan and humanist were at one, and the printing presses of Germany turned out a stream of literature against the abuses of the papal system. The movement spread so swiftly, especially in the north, that it seemed a single spontaneous popular outburst. But the harmony was soon broken. The rifts in the political and social organization of Germany were too deep to be spanned by any appeal to merely moral considerations. The Emperor Charles V, himself half-Spanish, set his face against a movement which was directly antagonistic to the Imperial tradition. The peasants revolted, committed excesses, and were ruthlessly crushed, and the violence of anabaptists and ignorant men threw discredit on the Lutheran cause. Then, too, dogmatic differences began to reveal themselves within the circle of the reformers themselves. There were disputes as to the exact significance and philosophic explanation of the Lord's Supper. A conference was held at Marburg, in 1529, under the auspices of Philip of Hesse, with a view to adjusting the differences between the divines of Saxony and Switzerland, but Luther and Zwingli failed to arrive at a compromise. The Lutheran and the Reformed Churches now definitely separated, and the divisions of the Protestants were the opportunity of the Catholic Church. The emperor tried in vain to reconcile Germany to the old faith. Rival theologians met, disputed, formulated creeds in the presence of temporal princes and their armed retainers. In 1530 the Diet of Augsburg forbade Protestant teaching and ordered the restoration of church property. Then a Protestant league was signed at Smalkald by John of Saxony, by Hesse, Brunswick-Luneberg, Anhalt, and several towns, and the emperor was defied. This was in 1531. It was the beginning of the religious wars of Germany, the beginning of that tremendous duel which lasted till the peace of Westphalia in 1648, the duel between the League of Smalkald and Charles V, between Gustavus Adolphus and Wallenstein, between the Protestant North and the Catholic South.