Few battles in world history provide a cleaner dividing line than Waterloo: before, there was Napoleon; after, there was the Pax Britannica. While Waterloo marked France’s defeat and Britain’s ascendance as an imperial power, the war was far from over for many soldiers and sailors, who were forced to contend with the lasting effects of battlefield trauma, the realities of an impossibly tight labour market, and growing social unrest. The Horrible Peace details a story of distress and discontent, of victory complicated by volcanism, and of the challenges facing Britain at the beginning of...