Tauentzien entered the Prussian Army in 1775 and was granted the title of Graf (count) on 5 August 1791. He became a royal aide-de-camp in 1793; he was entrusted with many diplomatic missions until 1813. Tauentzien participated in the campaign of 1793 and was successively promoted to Oberst in 1795 and Generalmajor in 1801. He commanded an observation corps of Friedrich Ludwig zu Hohenlohe-Ingelfingen until the Saalburg in 1806. Shortly before the Battle of Saalfeld, a French corps under Marshal Bernadotte defeated Tauentzien's detachment of 9,000 men at Schleiz. Tauentzien capably organized the retreat to Mittel-Pöllnitz so his troops could rejoin the main Prussian army.