In 1813–1814, the prince led the Danish Auxiliary Corps in Holstein. This was during the War of the Sixth Coalition, in which Denmark-Norway fought on the French side. The main task for his corps was to assist the forces of Louis-Nicolas Davout. When France suffered a loss at the Battle of Leipzig, Frederick's corps had to retreat, and in December 1813 he led his troops from Rostock to Rendsborg, saving the army from annihilation. He even led his troops to a victory in the Battle of Sehested on 10 December 1813. He then planned an attack on the Russian and Swedish occupational forces in Holstein. This attack was abandoned after the peace settlement between Sweden and Denmark-Norway, the Treaty of Kiel of 14 January 1814.