Casement served as British consul in Portugese East Africa (Mozambique) from 1895 to 1898, in Angola from 1898 to 1900, in the Congo Free State from 1901 to 1904, and in Brazil from 1906 to 1911.
His reports in 1904 and 1912, revealing cruelties and atrocities against native laborers perpetrated by white traders in the Congo and Putumayo River region of Peru, brought him international attention and led to a major reorganization of Belgian rule over the Congo. It was for his Putumayo Report that Casement received his knighthood. He retired from his overseas diplomatic labors in 1912, due to ill health, and returned to his native Ireland. Casement sympathized with the predominately Catholic Irish nationalists, despite his own Protestant upbringing. In 1913 he helped organize the anti-British, Irish National Volunteers. He sought American aid the organization. He traveled to Berlin in November 1914 to solicit an expedition to Ireland to fight against Britain, made up mostly of Irish P.O.W.s and lead by German officers. The German government was unwilling to back his project. There was considerable doubt as to whether the Irish P.O.W.s would fight.
On April 12, Casement sailed for Ireland aboard a German submarine. He was put ashore near Tralee, County Kerry. On April 21 he was discovered, arrested and taken to London. On June 29, he was convicted and sentenced to death for treason. Despite his past services to the crown and the efforts of many prominent people to obtain a reprieve for him, Casement was hanged in London on August 3rd, 1916.
An unfavorable biography: Roger Casement: a New Judgement by Rene Marie MacColl, 1956.
A favorable biography: The Accusing Ghost: or, Justice for Casement by Alfred Noyes, 1957.