World War I had many consequences. It is likely that, if you are asked to “list” them, your textbook provides such a list. I suggest that you look in your book or your notes for such a list.
For our purposes here, I will list three important consequences of this war. First, the war led to a loss of faith in humanity and the human potential on the part of many people. Europeans had come to believe that science and modernity could lead to constant human progress. The war seemed to show that this was not true. Second, the war led to a policy of isolationism in the United States. The US felt that it had been forced into a war that was none of its concern. It felt that it should have let Europeans deal with their own problems rather than getting involved. Therefore, as a result of the war, it withdrew from international affairs in the 1930s. Finally, and most importantly, WWI led to WWII. The aftermath of WWI made leaders in Germany and Japan, in particular, upset with the status quo. They pushed to change things and to give their countries positions of greater power and respect in the world. This led to WWII.
These are a few of the many consequences of World War I.