As Churchill explained, however, it was France who was key. When they folded in their diplomatic arrangements and followed England's lead following the Great War in the various treaties, they doomed themselves. Both Britain and France were first focused entirely on reparations (which Churchill opposed knowing they would engender more bad feelings) and then curiously they began to reverse course and appease nearly everything in the various treaty renegotiations leading up to Germany's invasion of Poland. What is also interesting is that up nearly until the invasion of Poland, Italy opposed Germany's intentions and Russia was Germany's ally in the invasion of Finland. Italy reversed course and sided with the Nazis when they were supported in their claims of dominance over Algiers, Tunisia, and most of North Africa, while Stalin and Russia were at least tacitly non-belligerent toward the Nazis until Hitler's failure to invade Britain forced him to look East for more land to conquer.

If you want a great primer on political machinations, the first book talking about the various agreements, treaties, and political decisions made between WW I and WW II is hard to beat.