What major events happened directly after World War 1?

There were several major events that happened after WW1. One was a type of influenza that killed over twenty million people world wide. Another major event was the formation of the League of Nations. The only major world power that did not join was the United States. The Congress at that time regressed to an isolationist mode. There is no evidence, however, that if the US was in the League of Nations that it would have resulted in any major change in the history of the world. Germany and Japan as an example simply dropped out of the League. The League was worthless and allowed more wars.