Sent to Spain in 1808 to join the Peninsular War, Colbert fought at the Battle of Medina del Rioseco on 14 July 1808 while serving under Marshal Jean-Baptiste Bessières. On 23 November, he led his cavalry at the Battle of Tudela under Marshal Jean Lannes. That winter, he commanded the 3rd Hussars and 15th Chasseurs in the cavalry advance guard of Marshal Nicolas Soult, who was pursuing Sir John Moore's British army in its retreat to A Coruña.