Charles August or Carl August (9 July 1768 – 28 May 1810) was a Danish prince. He is best known for serving as Crown Prince of Sweden briefly in 1810, adopted by Charles XIII, before his sudden death from a stroke. Earlier, he had been a general in the Royal Danish Army as well as the Governor-general of Norway. His name before assuming the Swedish title in 1810 was Christian August of Schleswig-Holstein-Sonderburg-Augustenburg, or Christian August of Augustenburg for short. Family He was born at Augustenborg Palace in July 1768 as the son of Friedrich Christian I, Duke of Schleswig-Holstein-Sonderburg-Augustenburg (1721–1794) and Princess Charlotte of Schleswig-Holstein-Sonderburg-Plön (1744–1770). He was a younger brother of Frederik Christian II, Duke of Augustenborg, brother-in-law of Princess Louise Auguste of Denmark and an uncle of Caroline Amalie of Augustenburg, Queen consort of Denmark and Christian August, Duke of Augustenborg. He did not marry. Career in Denmark and Norway Christian August studied in Leipzig, and returned from there to Denmark-Norway in 1785. He was appointed lieutenant colonel, and was promoted to colonel in 1787 and major general in 1790. From 1797 he was stationed in Austria, joining the fight against Napoleon. He left Austria when the Treaty of Lunéville ended the War of the Second Coalition in 1801. In 1803 Christian August was named commander of Fredriksten Fortress in Norway, assuming the position in 1804. In 1807 he once again became involved in the Napoleonic Wars, this time on the side of Napoleon as Napoleon's enemy Great Britain assaulted Denmark. The Danish-Norwegian part of the Napoleonic Wars is called the Gunboat War. Sweden joined forces against Denmark-Norway in 1808. Christian August was a central figure in the war, and led forces to victories in the Battle of Prestebakke and the Battle of Toverud, ousting Swedish forces from Norway. In 1808 Christian August was promoted to Field Marshal, and in 1809 he became Governor-general of Norway. Sweden On 6 June 1809 the Duke-regent of Sweden was proclaimed King, after Gustav IV Adolf was deposed. The new king Charles XIII accepted the new, liberal Constitution, which was ratified by the Riksdag of the Estates the same day. The new king was in no way likely to interfere with the liberal revolution which had placed him on the throne. Peace was what the exhausted nation now required. Charles XIII was childless, so in order to secure the succession to