A quick story on the Polar Bear Expeditionary Force sent to Russia at the end of WWI. The American Expeditionary Force, North Russia (AEF in North Russia) (also known as the Polar Bear Expedition) was a contingent of about 5,000 United States Army troops[1] that landed in Arkhangelsk, Russia as part of the Allied intervention in the Russian Civil War. It fought the Red Army in the surrounding region during the period of September 1918 through to July 1919.