At a conservative estimate, some 15m US citizens saw the moving pictures. A century on, this fragment of film provides a fascinating insight.
Casement is glimpsed at his desk writing: The daily activity he performed above any other. He used the pen like a sword, scripting damning criticisms of colonial misrule and political corruption.
But because most of his official reports and private correspondence remains unpublished, his historical meaning is suspended in a state of enigma, and his life and legacy draw a steady stream of interpretations.
There are biographical studies on his life in all major European languages. In 2012, Peruvian writer Mario Vargas Llosa, just weeks after he was awarded the Nobel Prize for Literature, published a fictionalised biography on Casement, The Dream of the Celt. The novel went viral. About 750,000 copies were distributed through the Spanish-speaking world.
Part of this international fascination for Casement extends from the fact that his legacy is not exclusive to Ireland; it belongs to many different regions of the globe.
He spent 20 years in sub-Saharan Africa, including over a decade working for the British Foreign Office, and was a consular official in Brazil for seven years.
His investigations of the brutality of Belgian king Leopold II’s Congo Free State, and his exposé of crimes against humanity in the Amazon rainforest, helped to define modern human rights discourse.
As a servant of empire, Casement travelled and observed how ordinary lives were ruined by the untrammelled forces of free market capitalism and the juggernaut of modernisation. Through observation and critical thinking, he was able to connect the experience of the Congo villager and the Amazon ‘Indian’ to the Connemara typhus victim.
Yet, despite the vast outpouring of interpretative writing on Casement, he remains a mysterious figure — full of paradoxes and contradictions. Because his official responsibilities, he preferred to stay out of the limelight.
His Foreign Office salary was used to fund secret republican causes such as Na Fianna Éireann, Irish-language schools, and low-circulation newspapers. He was a skilled and tireless networker in the lead-up to the Easter Rising, counting committed republicans Alice Milligan and Bulmer Hobson as close friends.
His acquaintance with the historian Alice Stopford Green introduced him to the medieval scholar Eoin MacNeill, the German philologist Kuno Meyer, and a busy circle of nationalist intellectuals in London.
He regularly visited the house of the Gaelic League organisers, Robert and Sylvia Lynd, in Hampstead.
Ulster was the Irish province he identified with most closely, regularly staying with relatives in the Glens of Antrim when home on leave. And when in Belfast, he enjoyed ceilídhs hosted by the antiquarian, Francis Joseph Bigger.
But as cultural nationalism was transformed by the deepening Home Rule crisis, Casement resigned from the Foreign Office and devoted his energies openly to Irish independence.
After the founding of the Irish Volunteers in 1913, Casement spoke at recruitment rallies across the country and accompanied Pádraig Pearse, Tomás MacDonagh, and Eoin MacNeill in building up the movement.
In late July 1914, by then in the US, he heard about the successful landing of guns at Howth by Erskine Childers and Mary Spring-Rice.
His key role in the planning of this venture gave him access to the inner circle of Clan na Gael, and, in November 1914, with the support of the IRB executive, he arrived in Berlin to promote and explain the Irish struggle, both politically and intellectually.
His efforts to recruit and train an Irish brigade, from among Irish-born British army prisoners of war in Germany, failed. He was cut off from his networks of international support.
Unwisely, he locked himself into a conspiratorial battle with the British Foreign Office — a contest he would inevitably lose.
In April 1916, returning to Ireland on board a German submarine (just ahead of the doomed shipment of guns sent from Berlin), Casement was captured at an old ringfort near Banna Strand in Kerry and spirited off to London to stand trial for high treason at the Royal Courts of Justice.
Guilty was the inevitable verdict. Despite many pleas for clemency, the noose quickly tightened around his neck. His prosecutor, FE Smith, a leading unionist, threatened to resign from the cabinet if the “traitor” did not hang.
But in death Casement proved even more controversial than he had in life. Strategies were activated by secret state agencies to use his sexuality to undermine his moral authority. Confusion and disagreement still entangle the spectre of the Black Diaries, purportedly written by Casement documenting his homosexual encounters with young men.
In 1965, as a mark of improving British-Irish relations, Casement’s bones were exhumed from an unmarked grave in Pentonville Prison and returned to Ireland.
President Éamon de Valera, defying his doctor’s orders, gave the oration at Casement’s state funeral in 1965, and assured the Irish people that the great patriot’s soul was now “in heaven”.
Angus Mitchell is author of Roger Casement in the 16 Lives biography series published by O’Brien Press. He edited and annotated ‘The Amazon Journal of Roger Casement’ and ‘Sir Roger Casement’s Heart of Darkness’. and has spent years researching Roger Casement. He has travelled widely in South America where he helped to curate a series of international exhibitions on Casement. Born in Africa, he now lives in Ireland.