As a step towards this end, Wallenstein now demanded the cession of
Mecklenburg, to be held in pledge till the repayment of his advances for
the war. Ferdinand had already created him Duke of Friedland,
apparently with the view of exalting his own general over Bavaria; but
an ordinary recompense would not satisfy Wallenstein's ambition. In
vain was this new demand, which could be granted only at the expense of
two princes of the empire, actively resisted in the Imperial Council; in
vain did the Spaniards, who had long been offended by his pride, oppose
his elevation. The powerful support which Wallenstein had purchased
from the imperial councillors prevailed, and Ferdinand was determined,
at whatever cost, to secure the devotion of so indispensable a minister.
For a slight offence, one of the oldest German houses was expelled from
their hereditary dominions, that a creature of the Emperor might be
enriched by their spoils (1628).

Wallenstein now began to assume the title of generalissimo of the
Emperor by sea and land. Wismar was taken, and a firm footing gained on
the Baltic. Ships were required from Poland and the Hanse towns to
carry the war to the other side of the Baltic; to pursue the Danes into
the heart of their own country, and to compel them to a peace which
might prepare the way to more important conquests. The communication
between the Lower German States and the Northern powers would be broken,
could the Emperor place himself between them, and encompass Germany,
from the Adriatic to the Sound, (the intervening kingdom of Poland being
already dependent on him,) with an unbroken line of territory. If such
was the Emperor's plan, Wallenstein had a peculiar interest in its
execution. These possessions on the Baltic should, he intended, form
the first foundation of a power, which had long been the object of his
ambition, and which should enable him to throw off his dependence on the
Emperor.