The Siege of Smolensk, in Polish (oblężenie Smoleńska) and known as the Smolensk Defense in Russia ("Смоленская оборона" in Russian), lasted 20 months between 29 September 1609 to 13 June 1611, when the Polish army besieged the Russian city of Smolensk during the Polish–Muscovite War (1605–1618).