For 10 points, name this 1939-1940 war during which the Soviet Union invaded Finland.
The winning side in this war withdrew from a city it had occupied during the war to prevent conflict with the British, who owned a license to the nickel mines in that city, Petsamo. The losing side in this war had built part of the Enckell Line, which was superseded by the Mannerheim Line. In a follow-up to the conflict called the Continuation War, the losing side attacked the Soviet Union concurrently with Germany's Operation Barbarossa and briefly regained Karelia and parts of Lake Ladoga. For 10 points, name this 1939-1940 war during which the Soviet Union invaded Finland.
The winning side in this war withdrew from a city it had occupied during the war to prevent conflict with the British, who owned a license to the nickel mines in that city, Petsamo.
{Winter} War [or {Russo}-{Finnish} War of 1939-1940 before "{Soviet Union}"]