 Lieven was sent to Caucasus and participated in the Persian Expedition and in the Georgian expedition.In 1797, Emperor Paul I made him his aide-de-camp, and in 1798 he was promoted to the rank of Major-general and assigned to the post of the Director of the Mobile Field Chancellery (военно-походная канцелярия) of His Majesty.Lieven accompanied Alexander I of Russia during the Battle of Vishkovo and Battle of Austerlitz and at the signing of the Peace of Tilsit.