He was thus thrown into opposition to the policy of Bismarck, and he was exposed to violent attacks in the Prussian press as a particularist, i.e., a supporter of the independence of the smaller states. Already in the aftermath of the Second Schleswig War, the expulsion of the Saxon troops from Rendsburg nearly led to a conflict with Berlin. On the outbreak of the Austro-Prussian War in 1866, Beust accompanied King John of Saxony on his escape to Prague, and thence to Vienna, where they were received by allied Emperor Franz Joseph with the news of Königgrätz. Beust undertook a mission to Paris to procure the help of Napoleon III. When the terms of peace were discussed he resigned, for Bismarck refused to negotiate with him.