Norman Angell was a British journalist, writer, and political theorist who is best known for his book "The Great Illusion," which was published in 1909, just a few years before the outbreak of World War I. In the book, Angell argued that war had become economically irrational and that the idea of using military power to achieve political ends was a "great illusion."
Angell believed that in the modern era, countries were so economically interdependent that war had become counterproductive. He argued that a country that went to war would suffer economically, and that this economic interdependence would prevent countries from using military power to achieve their goals. In his view, the costs of war had become so high that no country would be willing to engage in it.
Angell's argument was based on the assumption that countries would act rationally in their own self-interest, and that the economic consequences of war would outweigh any potential benefits. However, as events would later prove, this assumption proved to be incorrect, and World War I would demonstrate that military power remained a potent force in international politics. The outbreak of war in 1914 would prove Angell's ideas to be overly optimistic and unrealistic, and his views on the role of military power would be discredited by the devastating conflict that followed.