[16] Joseph Conrad's first impressions of Casement, from an encounter in the Congo he judged "a positive piece of good luck", was "thinks, speaks, well, most intelligent and very sympathetic".

[citation needed] In 1890 Casement met Joseph Conrad, who had come to the Congo to pilot a merchant ship, Le Roi des Belges ("King of the Belgians").

[21] In 1903 the Balfour Government commissioned Casement, then its consul at Boma in the Congo Free State, to investigate the human rights situation in that colony of the Belgian king, Leopold II.

Setting up a private army known as the Force Publique, Leopold had squeezed revenue out of the people of the territory through a reign of terror in the harvesting and export of rubber and other resources.

[citation needed] Casement travelled for weeks in the upper Congo Basin to interview people throughout the region, including workers, overseers and mercenaries.

The Belgian Parliament, pushed by Socialist leader Emile Vandervelde and other critics of the king's Congolese policy, forced Léopold to set up an independent commission of inquiry.

[26] He was attached as a consular representative to a commission investigating reports about an enslaved workforce collecting rubber for the Peruvian Amazon Company (PAC), which had been registered in Britain in 1907 and had a British board of directors and numerous stockholders.

Born in Rioja, Arana had climbed out of poverty to own and operate a company harvesting great quantities of rubber in the Peruvian Amazon, which was much in demand on the world market.

For years, the Indians had been forced into unpaid labour by field staff of the PAC, who exerted absolute power over them and subjected them to near starvation,[b] severe physical abuse, rape of women and girls by the managers and overseers, terrorization and casual murder.

Casement's report has been described as a "brilliant piece of journalism", as he wove together first-person accounts by both "victims and perpetrators of atrocities ... Never before had distant colonial subjects been given such personal voices in an official document.

In a report to the British foreign secretary, dated 17 March 1911, Casement detailed the rubber company's continued use of pillories to punish the Indians:Men, women, and children were confined in them for days, weeks, and often months.

[50] After his return to Britain, Casement repeated his extra-consular campaigning work by organising interventions by the Anti-Slavery and Aborigines' Protection Society and Catholic missions in the region.

[56] In Ireland in 1904, on leave from Africa from that year until 1905, Casement joined the Gaelic League, an organisation established in 1893 to preserve and revive the spoken and literary use of the Irish language.

Casement was more impressed by Arthur Griffith's new Sinn Féin party (founded 1905), which called for an independent Ireland (through a non-violent series of strikes and boycotts).

These included Ada McNeil, with whom Casement helped organise the first Feis na nGleann (Festival of the Glens) at Waterfoot (County Antrim) in 1904,[59] Bulmer Hobson (later of the IRB), the Nationalist MP Stephen Gwynn, and the Gaelic League activist Alice Milligan.

B. Armour, he spoke to the motion disputing the claim of Edward Carson and his unionists "to represent the Protestant community of North East Ulster", and condemning the prospect of "lawless resistance" to Home Rule.

[67] Meanwhile an anti-Home Rule meeting addressed by Carson's lieutenant Sir James Craig, then organising the Ulster Volunteers, not only filled the Ballymoney Town Hall but had the crowd spilling out into the surrounding streets.

[67] Already in November 1913, Casement had begun focussing on responding to "Carsonism" in kind: he became a Gaelic League member of the Provisional Committee of the Irish Volunteers launched at a meeting in the Rotunda in Dublin.

[70] In April 1914, he had been together with Alice Milligan in Larne shortly after Craig had had German guns run through the port, a feat Casement told her nationalists would have to match.

[72] Elements of the suspicious Clan did not trust Casement completely, as he was not a member of the IRB and held views that they considered too moderate but others, such as John Quinn, regarded him as extreme.

In August 1914, at the outbreak of World War I, Casement and John Devoy arranged a meeting in New York with the western hemisphere's top-ranking German diplomat, Count Bernstorff, to propose a mutually beneficial plan: if Germany would sell guns to the Irish revolutionaries and provide military leaders, the Irish would revolt against England, diverting troops and attention from the war with Germany.

[79] This letter—written on official notepaper by Minister Findlay at the British Legation in Oslo—offered to Christensen the sum of £5,000 (equivalent to £606,100 in 2023) plus immunity from prosecution and free passage to the United States in return for information leading to the capture of Roger Casement.

During World War I, Casement is known to have been involved in the German-backed plan by Indians to win their freedom from the British Raj, the "Hindu–German Conspiracy", recommending Joseph McGarrity to Franz von Papen as an intermediary.

In addition to finding it difficult to ally with the Germans while held as prisoners, potential recruits to Casement's brigade knew they would be liable to the death penalty as traitors if Britain won the war.

Evidently abandoning the Irish Nationalist cause, he joined the Royal Navy in 1916, survived the war, and later returned to the United States, where he died in an accident on a building site in 1925.

[92] In the early hours of 21 April 1916, three days before the rising began, the German submarine put Casement and his two companions ashore at Banna Strand in Tralee Bay, County Kerry – the boat used is now in the Imperial War Museum in London.

[citation needed] A United States Senate appeal against the death sentence was rejected by the British cabinet on the insistence of prosecutor F. E. Smith, an opponent of Irish independence.

A private report on the authenticity of the Black Diaries was commissioned by Professor William J. McCormack of Goldsmiths College, jointly funded by the BBC and RTE, and carried out by Dr. Audrey Giles.

As late as July 2015 the UK National Archives ambiguously described the Black Diaries as "attributed to Roger Casement", while at the same time unambiguously declaring their satisfaction with the result of the private Giles Report.

Hyde wrote that "Mr. Dudgeon’s confusion about the alleged authenticity of the ledger is understandable but it’s a fact that he published the compromising sentence for 17 years before deleting it without explanation in his third edition.