During the brief regency of
Anna Leopoldovna (October 1740-December 1741) Ostermann stood at the height of his power, and the French ambassador,
Marquis de La Chetardie, reported to his court that "it is not too much to say that he is tsar of all Russia" Ostermann's foreign policy was based upon the Austrian alliance. He had, therefore, guaranteed the Pragmatic Sanction with the deliberate intention of defending it. Hence the determination of France to remove him at any cost. Russia, as the natural ally of
Austria, was very obnoxious to
France; indeed it was only the accident of the Russian alliance which, in 1741, seemed to stand between
Maria Theresa of Austria and absolute ruin. The most obvious method of rendering the Russian alliance unserviceable to the queen of
Hungary was by implicating Russia in hostilities with her ancient rival, Sweden, and this was brought about, by French influence and French money, when in August 1741 the Swedish government, on the most frivolous pretexts, declared war against Russia. The dispositions previously made by Ostermann enabled him, however, to counter the blow, and all danger from Sweden was over when, early in September,
Field-Marshal Lacy routed the Swedish general von Wrangel under the walls of the frontier-fortress of
Villmanstrand, which was carried by assault. ==Downfall==