1809 was a year:
- 17 September 1809: Russia and Sweden sign the Treat of Hamnia, ending the Finnish War. Sweden cedes Finland.
- Göran Frilund. "The Union's Last War: The Russian-Swedish War of 1808-09" (in English). Napoleon Series. https://www.napoleon-series.org/military-info/battles/c_finnish.html. Retrieved 18 March 2021.