The duchy was occupied by French troops in 1803–05, after which the French occupational troops left in a campaign against Austria. Then British, Swedish and Russian Coalition forces captured Saxe-Lauenburg in autumn 1805 at the beginning of the War of the Third Coalition against France (1805–06). In December the Empire of the French, since 1804 France's new form of government, ceded Saxe-Lauenburg, which it no longer held, to Brandenburg-Prussia, which captured it early in 1806.