"A bold and provocative history of how an overlooked 1923 treaty was among the most transformative events in modern history. On a hot summer afternoon in 1928, the leaders of the world assembled in Paris to outlaw war. Within the year, the treaty signed that day, known as the Peace Pact, had been ratified by nearly every state in the world. War, for the first time in history, had become illegal the world over. But the promise of that summer day was fleeting. Within a decade of the signing of the Pact, each state that had gathered in Paris to renounce war was at war. And in the century that followed, the Peace Pact was dismissed as an act of folly and an unmistakable failure. This book argues that that understanding is inaccurate, and that the Peace Pact ushered in a sustained march toward peace that lasts to this day. [This book] tells the story of the Peace Pact by placing it in the long history of international law from the seventeenth century through the present. It details the brutal world of conflict the Peace Pact helped extinguish and the subsequent era where tariffs took the place of tanks. Accessible and gripping, this hook will change the way we view the history of the twentieth century--and show how we must work together to protect the global order the internationalists fought to make possible."--Jacket.