After the peace of Tilsit he became governor of Berlin, and in 1808 he was created duke of Belluno (the title was extinguished in 1853). In the same year he was sent to Spain, where he took a prominent part in the Peninsular War (especially against Blake at the Battle of Espinosa, and later at the battles of Talavera, Barrosa and Cádiz), until his appointment in 1812 to a corps command in the invasion of Russia. At first his corps was posted in the east Prussia but it was later moved up to Smolensk support the invading forces. From here his most important service was in protecting the retreating army at the crossing of the Berezina River.