In what ways can I prove that the failure of collective security, in the inter-war period, led to world war II?

How were national interest in any way affected with the use of collective security?In what ways can I prove that the failure of collective security, in the inter-war period, led to world war II?Collective security proved not to work unless all the great powers were in agreement. When they were not, it was useless. For example, Japan took Manchuria off China and then went after China proper. Both were members of the League of Nations, which did nothing. Same with Italy conquering Ethiopia. In these cases, the leading members of the League, just stood by. When the civil war broke out in Spain, Italy and Germany actively supported the Nationalists, including sending troops. Britain and France put on a supposed embargo of both sides that only hurt the legitimate Republican government. Finally, France, Britain and Italy all actively supported Germany in taking the Sudetenland from Czechoslovakia. So, small states learned they had to look to their own interests and find a great power protector. Most of central Europe chose Germany as a protector. Poland found itself caught between Germany and the Soviet Union and went down to invasions from both. Norway, Denmark, Belgium and Holland all tried to stay neutral and refused any military cooperation with Britain and France until the Germans attacked them, by which time it was too late.