There are more than 200 million words of agreement that collectively give form to the international system, organize relations between states, and which cumulatively, and ever more closely, bind its peoples together. Over the last four centuries, these words have been negotiated, debated, challenged, refuted, clarified, and made legally and mutually understandable before becoming formally enshrined in one of the 79,287 international treaties signed during this period.Simultaneously, and despite some notable exceptions, the world has become an increasingly peaceful and cooperative place, with interstate warfare declining gradually around the world and then rapidly after 1945. This project seeks to better understand why this global paradigmatic transformation has occurred and how it has been affected by the negotiation, signing, and implementation of tens of thousands of international treaties over time.Many existing studies have difficulty in explaining long-term change and either tend to assume that war is inevitable due to the supposedly immutable condition of anarchy, emphasize developments that have occurred too recently to explain the longer-term trends, or focus on a small subset of the most important multilateral treaties in history to the relative exclusion of all the important treatymaking effects and gradual changes that happen at every stage in between.Explanations for why interstate wars are so infrequent today, when they were a major and widely accepted instrument of foreign policy throughout most of history, have been stymied by our inability to fully appreciate and meaningfully incorporate the complex expanding totality of international law over time and its cumulative pacific effects on international relations.This project was able to overcome these challenges by leveraging artificial intelligence, new data, and machine-learning algorithms, to systematically analyze and visualize four centuries worth of international treaties, and to provide significant new contributions to our understanding 4 of how the international system has become more organized and peaceful over time. Using computational treaty analysis, each agreement was classified by topic, signatories, and a variety of additional metrics to measure absolute and relative changes in the formal, legal aspects of the international system over time, which can now be seen accumulating over the centuries like so many strata preserved in the historical "fossil record" of international relations. By compiling, translating, processing, and visualizing the 79,287 recently digitized treaties signed between 1648 and 2022, this dissertation vividly illustrates the incremental but consistent change in the structure of international order and provides a window into the past regarding what the dominant concerns of international law and relations were over the last four centuries, what they are today, and how they have changed over this period. This expansive and algorithmically analyzed record of international law chronicles a broad range of formal inters...