 In the service of the Russian Empire, Clausewitz helped negotiate the Convention of Tauroggen (1812), which prepared the way for the coalition of Prussia, Russia, and the United Kingdom that ultimately defeated Napoleon and his allies.In 1815 the Russian-German Legion became integrated into the Prussian Army and Clausewitz re-entered Prussian service as a colonel.He was soon appointed chief-of-staff of Johann von Thielmann's III Corps.