This introduction presents an overview of the key concepts covered in the subsequent chapters of this book. The book explains various disciplines together to assess the history and on-going relevance of the Hague conferences, the conventions they brought into being, the institutions they established, the precedents they set, the people they influenced and the ideas they shaped. It discusses reassessment of the 1899 and 1907 Hague conferences' importance as essential moments in determining the shape of international history in the twentieth and twenty-first centuries. The book highlights the power of legal norms in the international system by analysing the impact of the 1899 Hague Convention. It focuses on the ways in which The Hague's principles shaped understandings about the application of the rules of war and set norms for military conduct against civilians. The book also presents an extraordinary history of the power of the Hague conventions to shape domestic legal developments.