Question

Why is WWI considered the war to end all wars? What does this mean?

Answer 1

At the time, World War I was the most destructive war in human history. People of the time began referring to it as "the war to end all wars" partially to encompass the totality of destruction but also a way to ward off any future war. Modern readers know that this was not successful and the world had to endure another massively destructive world war twenty years later.