This, which may be regarded as the greatest period of the Thirty Years' War, was characterized by the appearance on the scene of Gustavus Adolphus, the Swedish King.

He was not in time, however, to prevent the sacking of Magdeburg by the troops of Tilly and Poppenheim.

The former, nevertheless, was defeated by the Swedes at the important battle of Breitenfeld in 1631.

The following year the Imperial army was again defeated on the Lach.

Thereupon Gustavus occupied Muenchen, though he was subsequently compelled by Wallenstein to evacuate the city.