World War II triggered widespread suffering and changes globally, particularly impacting Jewish and disabled populations who faced extermination at the hands of Nazi forces. The war, beginning with Germany's invasion of Poland, involved brutal tactics and had significant geopolitical consequences, while highlighting the necessity of interventionism to prevent future humanitarian disasters. Ultimately, the war reshaped the world order, advanced military technology, and catalyzed social changes, including shifts in gender roles and economic structures in the U.S.