Baron Percy's campaign journal presents a surgeon's view of war during the Napoleonic era. Pierre-François Percy, chief surgeon of the Grande Armée, records the pressures of battlefield medicine: triage, amputations, disease, evacuation, shortages, and the organization of medical services amid rapid military movement. The journal is valuable as a firsthand account of how one of the period's leading medical practitioners understood the human cost of campaign warfare. Readers encounter the practical realities of early nineteenth-century army medicine, from improvised treatment under fire to the administration of hospitals and the logistics of caring for wounded soldiers across long marches. The account also sheds light on the relationship between medicine, command, morale, and survival in Napoleon's armies. As a historical source, it offers a grounded, often unsentimental perspective on the Napoleonic Wars through the experience of a physician whose work placed him close to both suffering and decision-making.