Arkhangelsk's economy revived at the end of the 19th century when a railway to Moscow was completed and timber became a major export. The city resisted Bolshevik rule from 1918 to 1920 and was a stronghold of the anti-Bolshevik White Army supported by the military intervention of British-led Entente forces along an Allied expedition, including a North American contingent known as the Polar Bear Expedition. It was also the scene of Mudyug concentration camp.