"The Great Illusion" by Norman Angell is a book first published in 1909. Angell argues that modern war between industrial nations is economically futile because conquest brings no real gain. He contends that international economic interdependence makes armed conflict irrational and self-defeating. The book became a bestseller, spawning study groups and influencing military leaders. Yet World War I erupted just years later, leading many to dismiss Angell's ideas—though scholars later recognized the work as foundational to understanding international relations.