s driven to the
most humiliating and desperate expedients, to return to the history of
the Emperor.

As soon as the plan of operations had been concerted at Halle, between
the King of Sweden and the Elector of Saxony; as soon as the alliance
had been concluded with the neighbouring princes of Weimar and Anhalt,
and preparations made for the recovery of the bishopric of Magdeburg,
the king began his march into the empire. He had here no despicable foe
to contend with. Within the empire, the Emperor was still powerful;
throughout Franconia, Swabia, and the Palatinate, imperial garrisons
were posted, with whom the possession of every place of importance must
be disputed sword in hand. On the Rhine he was opposed by the
Spaniards, who had overrun the territory of the banished Elector
Palatine, seized all its strong places, and would everywhere dispute
with him the passage over that river. On his rear was Tilly, who was
fast recruiting his force, and would soon be joined by the auxiliaries
from Lorraine. Every Papist presented an inveterate foe, while his
connexion with France did not leave him at liberty to act with freedom
against the Roman Catholics. Gustavus had foreseen all these obstacles,
but at the same time the means by which they were to be overcome. The
strength of the Imperialists was broken and divided among different
garrisons, while he would bring against them one by one his whole united
force. If he was to be opposed by the fanaticism of the Roman
Catholics, and the awe in which the lesser states regarded the Emperor's
power, he might depend on the active support of the Protestants, and
their hatred to Austrian oppression. The ravages of the Imperialist and
Spanish troops also powerfully aided him in these quarters; where the
ill-treated husbandman and citizen sighed alike for a deliverer, and
where the mere change of yoke seemed to promise a relief. Emissaries
were despatched to gain over to the Swedish side the principal free
cities, particularly Nuremberg and Frankfort. The first that lay in the
king's march, and which he could not leave unoccupied in his rear, was
Erfurt. Here the Protestant party among the citizens opened to him,
without a blow, the gates of the town and the citadel. From the
inhabitants of this, as of every important place which afterwards
submitted, he exacted an oath of allegiance, while he secured its
possession by a sufficient garrison. To his ally, Duke William of
Weimar, he intru