 Frederick Augustus also did not participate in the creation of the Confederation of the Rhine, which led to the final dissolution of the Holy Roman Empire.With respect to the Prussian idea of a north German empire, within which Saxony was supposed to be raised to a kingdom, he appeared reserved.However, when Napoleon advanced as far as Thuringia after September 1806 in response to the Berlin Ultimatum, which demanded the withdrawal of French troops from the left bank of the Rhine, Frederick Augustus joined with Prussia.