March 31st, 1939: France signs a treaty of mutual assistance with Poland in response to German defiance of the Munich Agreement, thereby guaranteeing Polish independence in the event of German aggression against Poland.
Notably missing from the treaty is the United Kingdom, which has declined to guarantee the independence of Poland and has instead opted to avoid war with Germany.
Could this have happened? What would be the implications for Europe, Anglo-French relations and the world if it did? What would be the outcome of this war?