Soviet poster commemorating Finland's defeat in the Winter War. The text reads: "Reference [as in memorandum]: Beaten on the Mannerheim Line in 1940." The Mannerheim Line, named for Marshal of Finland Baron Carl Gustaf Emil Mannerheim (June 4, 1867 - January 27, 1951), was a series of trenches and log dugouts that were constructed from 1921-1939, running from the Gulf of Finland to Lake Lagoda. The Line held against repeated Soviet attacks from December 1939 to February 1940. Lacking coordination, trained officers, and winter supplies, the Soviets only broke through with massed tanks and infantry following huge artillery barrages. Estimates of Soviet losses range wildly, with official sources claiming 54,000 casualties. Political Commissar (later Soviet Premier) Nikita Sergeyevich Khrushchev (April 15, 1894 - September 11, 1971) estimated the Red Army incurred one million casualties, but most historians believe the Soviets lost 80-100,000 men. The Finns lost 25,904 killed and 43,557 wounded.