In 1903, Roger Casement, then a British consul, left his consular base on the Lower Congo River and made a journey through the regions of the Upper Congo to investigate at first hand reports of alleged atrocities. His subsequent report was a crucial instrument in the British government’s efforts to bring about change in King Leopold’s Congo Free State. This edition brings together Casement’s report, together with his diary of that year, which have been carefully edited for publication. Names which were omitted from the original published report have been reinstated, and explanatory notes have been provided to report and diary. The editors’ introduction addresses the scramble for Africa, the role of Leopold and the Congo Free State, Britain and the Congo question, Casement’s career, publication of the report and the humanitarian campaign, 1904-13.