Sir Roger Casement, in full Sir Roger David Casement, diplomat and Irish nationalist, is born on September 1, 1864, in Kingstown (now Dún Laoghaire), County Dublin. Following his execution for treason in 1916, he becomes one of the principal Irish martyrs in the revolt against British rule in Ireland.

Casement is born into an Anglo-Irish family, and lives his very early childhood at Doyle’s Cottage, Lawson Terrace, Sandycove. His father, Captain Roger Casement of the (King’s Own) Regiment of Dragoons, is the son of Hugh Casement, a Belfast shipping merchant who goes bankrupt and later moves to Australia. After the family moves to England, Casement’s mother, Anne Jephson (or Jepson), of a Dublin Anglican family, purportedly has him secretly baptised at the age of three as a Roman Catholic in Rhyl, Wales.

The family lives in England in genteel poverty. Casement’s mother dies when he is nine years old. His father takes the family back to County Antrim in Ireland to live near paternal relatives. His father dies when he is thirteen years old. He is educated at the Diocesan School, Ballymena (later the Ballymena Academy). He leaves school at 16 and goes to England to work as a clerk with Elder Dempster Lines, a Liverpool shipping company headed by Alfred Lewis Jones.

Casement is a British consul in Portuguese East Africa (1895–98), Angola (1898–1900), Congo Free State (1901–04), and Brazil (1906–11). He gains international fame for revealing atrocious cruelty in the exploitation of native labour by white traders in the Congo and the Putumayo River region of Peru. His Congo report, published in 1904, leads to a major reorganization of Belgian rule in the Congo in 1908, and his Putumayo report of 1912 earns him a knighthood, which is ultimately forfeited on June 29, 1916.

Ill health forces Casement to retire to Ireland in 1912. Although he comes from an Ulster Protestant family, he has always sympathized with the predominantly Roman Catholic Irish nationalists. Late in 1913 he helps form the National Volunteers, and in July 1914 he travels to New York City to seek American aid for that anti-British force. After World War I breaks out in August, he hopes that Germany might assist the Irish independence movement as a blow against Great Britain. On arriving in Berlin in November 1914, he finds that the German government is unwilling to risk an expedition to Ireland and that most Irish prisoners of war would refuse to join a brigade that he intends to recruit for service against England.

Later, Casement fails to obtain a loan of German army officers to lead the Irish rising planned for Easter 1916. In a vain effort to prevent the revolt, he sails for Ireland on April 12 in a German submarine. Put ashore near Tralee, County Kerry, he is arrested on April 24 and taken to London, where, on June 29, he is convicted of treason and sentenced to death. An appeal is dismissed, and he is hanged at London’s Pentonville Prison on August 3, 1916, despite attempts by influential Englishmen to secure a reprieve in view of his past services to the British government. During this time, diaries reputedly written by Casement and containing detailed descriptions of homosexual practices are circulated privately among British officials. After years of dispute over their authenticity, the diaries are made available to scholars by the British home secretary in July 1959. It is generally considered that the passages in question are in Casement’s handwriting.

In 1965 Casement’s remains are repatriated to Ireland. Despite the annulment, or withdrawal, of his knighthood in 1916, the 1965 UK Cabinet record of the repatriation decision refers to him as “Sir Roger Casement.”

Casement’s last wish is to be buried at Murlough Bay on the north coast of County Antrim, in present-day Northern Ireland, but Prime Minister Harold Wilson‘s government had released the remains only on condition that they could not be brought into Northern Ireland, as “the government feared that a reburial there could provoke Catholic celebrations and Protestant reactions.”

Casement’s remains lay in state at the Garrison Church, Arbour Hill (now Arbour Hill Prison) in Dublin for five days, close to the graves of other leaders of the 1916 Easter Rising. After a state funeral, his remains are buried with full military honours in the Republican plot in Glasnevin Cemetery in Dublin, alongside other Irish republicans and nationalists. The President of Ireland, Éamon de Valera, then the last surviving leader of the Easter Rising, attends the ceremony, along with an estimated 30,000 others.