Wargaming—the simulation of complex war situations—is becoming increasingly more relevant to political and military discourse as U.S. armed forces lean more heavily on it as a training tool to hone warfighters’ decision-making skills and to shape defense plans and policies. And while wargaming can be useful for informing predictions of future military conflicts, it is also an excellent tool for understanding past conflicts. Wargaming Waterloo explores three key aspects of wargaming as a practice by focusing on the iconic battle that led to Napoléon Bonaparte’s defeat in 1815. A longtime subject of both fascination and controversy, the Battle of Waterloo presents particular problems as a board, map, or tabletop wargame and also poses a serious research question: just how good a chance did Napoléon have at victory when he confronted the duke of Wellington at Mont Saint-Jean and how would the strategic situation have to be different to enable Napoléon to prevail?