Franco-British plans for intervention in the Winter War

Finland's resistance to the Soviet invasion, from November 1939 to March 1940, came while there was a military stalemate on the continent called the "Phony War".

Months of planning at the highest civilian, military and diplomatic levels in London and Paris saw multiple reversals and deep divisions.

[4] "American opinion makers treated the attack on Finland as dastardly aggression worthy of daily headlines, which thereafter exacerbated attitudes toward Russia".

[5] The real Allied goal was economic warfare: to cut off shipments of Swedish iron ore to Germany, which was calculated to weaken German war industry seriously.

The British military leadership, by December, had supported the idea enthusiastically after it had realised that its first choice, an attack on German oil supplies, would not get approval.

Winston Churchill, now leading the Admiralty, pushed hard for an invasion of Norway and Sweden to help the Finns and to cut the iron supplies.

[7] The first intervention plan, approved on 4–5 February 1940 by the Allied High Command, consisted of 100,000 British and 35,000 French troops, which would disembark at the Norwegian port of Narvik and support Finland via Sweden while they secured supply routes along the way.

Plans were made to launch the operation on 20 March under the condition of a formal request for assistance from the Finnish government to avoid German charges that the Franco-British forces were an invading army.

The planned frontier involved Sweden's two largest cities but also could result in large amounts of Swedish territory to be occupied by a foreign army or to become a war zone.

By the end of that month, Finnish Commander-in-Chief, Field Marshal Mannerheim was pessimistic about the military situation and on 29 February, the government decided to start peace negotiations.

On 20 March, a more aggressive Paul Reynaud became prime minister of France and demanded an immediate invasion; Chamberlain and the British cabinet finally agreed and orders were given of Operation Wilfred to provoke a justification.

[10] However, Germany invaded first and quickly conquered Denmark and southern Norway in Operation Weserübung, repelling Allied counter-efforts in Scandinavia.