Louis Antoine was unable to prevent Napoleon's return to Paris as chief of the royalist army in the southern Rhône River valley, and he was again forced to flee to Britain during the "Hundred Days". He loyally served Louis XVIII after the final defeat of Napoleon at Waterloo. In 1823, he commanded a French army sent into Spain to restore the King's absolute powers, known as the Hundred Thousand Sons of Saint Louis. He was victorious in the Battle of Trocadero, after which the reactionary power of King Ferdinand VII of Spain was firmly restored. For this achievement, he was awarded the title of a "Prince of Trocadero".