He became "aide-de-camp" to Marshal Pierre Augereau on 31 August 1803 and was promoted to the rank of lieutenant on 11 July 1804. During the war against the Kingdom of Prussia and the Russian Empire between 1806 and 1807, he fought in the VII corps of the "Grande Armée". Having distinguished himself at the Battle of Austerlitz, he was promoted to the rank of captain on 3 January 1807. The following month, he took part in the Battle of Eylau, during the course of which he nearly lost his life. After this he served in the Peninsular War under Marshals Jean Lannes and André Masséna, and showed himself to be a dashing leader of light cavalry in the Russian campaign of 1812.