Winter War. To observe the correct diplomatic etiquette before declaring war, USSR withdraws from its non-aggression pact with Finland, amid further Finnish protests. The Soviets maintain that Finland is the aggressor, despite a Finnish investigation revealing that Finnish border guards witnessed the shelling of Mainila by Soviet mortars.
Battle of the Atlantic. In the North Sea, Royal Navy trawler HMS Kingston Beryl scuttles the stern section of SS Gustaf E. Reuter which was torpedoed by U-48 on November 27.