In 1867 Alfred LaRocque, a young Quebecker, left home to defend the papacy in Rome. In 1937 journalist and communist Jean Watts travelled to Spain to cover the civil war. In 2023 former corporal Kyle Porter took up arms in Ukraine. Separated by time and cause, the three share a bond with tens of thousands of Canadians who fought, assisted, or died defending other nations or oppressed peoples. The stories of transnational fighters complicate Canada’s familiar war narrative, illuminating the motivations and passions that drove people to fight abroad and the legal and political legacies that followed them home. Spanning 150 years, Wars of Conviction explores who fought, why they did so, and what they experienced during and after battle. Canadians’ decisions to take up arms in the Papal Zouaves, the Spanish Civil War, the Sino-Japanese War, Vietnam, Syria, and Ukraine provoked both admiration and outrage, invited state scrutiny, and sparked enduring debate over how such fighters should be commemorated. A deftly sketched portrait of the fighters that committed to making foreign wars their own, this volume unsettles military history to better understand an uncertain present.