After moving to the French Army of Hanover, Philippon was made a member of the Légion d'honneur on 19 Frimaire Year XII (November 1803) and an officer of that order on 25 Prairial (14 June 1804). He served in Spain during the Peninsular War from 1808, was created a baron in 1809, and saw action with General Pierre Lapisse's division of Marshal Victor's I Corps at the Battle of Talavera and the Siege of Cádiz. Philippon's conduct at Cádiz resulted in his promotion to Brigadier General ("Général de Brigade") on 25 June 1810.