Political map of Europe & the Mediterranean 21 April 1940 (Invasion of Denmark and Norway): For over six months after the invasion of Poland (Invasion of Poland (1939)), no major land fighting occurred in the West - leading to claims that this would be a 'Phoney War' (Phoney War). Then in April, Germany suddenly invaded Denmark and Norway (Operation Weserubung). The Allies, who had been preparing to land in Norway themselves to belatedly aid the Finns against Russia (Winter War), were caught by surprise. It was a feeling they were going to have to get used to.