I would agree that breakdown of the multi-polar distribution of power between 1914-1945 was more or less inevitable. To understand what was going on, however, we need to head back to the nineteenth century. Through most of the nineteenth century, from the end of the Napoleonic Wars in 1815, Great Britain was the world's undisputed superpower. Britain had the largest, most powerful navy in the world. It was the undisputed ruler of the seas. It had a huge and lucrative empire, spread across the globe. It also was the first country to take-off into industrialism, giving it a huge head start in wealth creation. It is difficult to overstate how immensely wealthy and powerful the country was.
When one country is that powerful, it usually leads to peace, because no other country is suicidal enough to challenge its power. If a country does, it is quickly crushed, sending the message to other nations not to start trouble. Thus, through most of the nineteenth century, a "Pax Brittanica" prevailed. However, by the end of the century, Britain was showing signs of weakness. The Boer War was a mismanaged disaster, and other countries were rapidly catching up in industrial strength and establishing their own overseas empires. Most particularly, Germany unified. It gained territory in the Franco-Prussian war. It too industrialized and wanted to use its new wealth to challenge Britain's control of the seas.
As Germany strengthened and Britain weakened, struggling to hang on to its top-dog position, a clash was almost inevitable. It came in the form of World War I. That war, however, failed to solve any fundamental problems. Power became multi-polar, Britain continued to wane, and Germany rearmed under Hitler. The United States, which everyone understood was poised to be the new super power, remained in the shadows, immersed in isolationism until World War II. This unstable situation, in which it was unclear who was going to win the global power stakes in Europe, led to the war that finally rearranged the global European order.