At the Congress of Erfurt (September–October 1808) Napoleon and Alexander agreed that Russia should force Sweden to join the Continental System, which led to the Finnish War of 1808–1809 (meaning Sweden played no role in the next coalition against Napoleon) and to the division of Sweden into two parts separated by the Gulf of Bothnia. The eastern part became the Russian Grand Duchy of Finland. Due to the Continental System, Britain was yet again still at war with Napoleon and was not affected by the peace treaty.