into Silesia, and it was
his intention to carry his ravages even into Moravia and Austria. But
to prevent this, Count Hatzfeld was summoned from Westphalia, and
Piccolomini from the Netherlands, to hasten with all speed to this
quarter. The Archduke Leopold, brother to the Emperor, assumed the
command, in order to repair the errors of his predecessor Gallas, and to
raise the army from the low ebb to which it had fallen.

The result justified the change, and the campaign of 1640 appeared to
take a most unfortunate turn for the Swedes. They were successively
driven out of all their posts in Bohemia, and anxious only to secure
their plunder, they precipitately crossed the heights of Meissen. But
being followed into Saxony by the pursuing enemy, and defeated at
Plauen, they were obliged to take refuge in Thuringia. Made masters of
the field in a single summer, they were as rapidly dispossessed; but
only to acquire it a second time, and to hurry from one extreme to
another. The army of Banner, weakened and on the brink of destruction
in its camp at Erfurt, suddenly recovered itself. The Duke of Lunenburg
abandoned the treaty of Prague, and joined Banner with the very troops
which, the year before, had fought against him. Hesse Cassel sent
reinforcements, and the Duke of Longueville came to his support with the
army of the late Duke Bernard. Once more numerically superior to the
Imperialists, Banner offered them battle near Saalfeld; but their
leader, Piccolomini, prudently declined an engagement, having chosen too
strong a position to be forced. When the Bavarians at length separated
from the Imperialists, and marched towards Franconia, Banner attempted
an attack upon this divided corps, but the attempt was frustrated by the
skill of the Bavarian General Von Mercy, and the near approach of the
main body of the Imperialists. Both armies now moved into the exhausted
territory of Hesse, where they formed intrenched camps near each other,
till at last famine and the severity of the winter compelled them both
to retire. Piccolomini chose the fertile banks of the Weser for his
winter quarters; but being outflanked by Banner, he was obliged to give
way to the Swedes, and to impose on the Franconian sees the burden of
maintaining his army.

At this period, a diet was held in Ratisbon, where the complaints of the
States were to be heard, measures taken for securing the repose of the
Empire, and the question of peace or war finally s