Answer:
The world was plunged into WWII in 1939, because the appeasement did not work and Hitler kept expanding, and it got to the point where no one could stop him. This is why we need the collective security, to bring nations to stop Hitler. Sol it was because of Hitlers expansions that we had to go into WWII.
Explanation:Hope this helps if not then check with google. Have a nice day.
