British diplomat turned Irish nationalist Roger Casement is sentenced to death for his part in the Easter Rising.

A diplomat is a person appointed by a state, intergovernmental, or nongovernmental institution to conduct diplomacy with one or more other states or international organizations.

Irish nationalism is a nationalist political movement which, in its broadest sense, asserts that the people of Ireland should govern Ireland as a sovereign state. Since the mid-19th century, Irish nationalism has largely taken the form of cultural nationalism based on the principles of national self-determination and popular sovereignty. Irish nationalists during the 18th, 19th, and 20th centuries such as the United Irishmen in the 1790s, Young Irelanders in the 1840s, the Fenian Brotherhood during the 1880s, Fianna Fáil in the 1920s, and Sinn Féin styled themselves in various ways after French left-wing radicalism and republicanism. Irish nationalism celebrates the culture of Ireland, especially the Irish language, literature, music, and sports. It grew more potent during the period in which all of Ireland was part of the United Kingdom, which led to most of the island gaining independence from the UK in 1922.

Roger David Casement, known as Sir Roger Casement, CMG, between 1911 and 1916, was a diplomat and Irish nationalist executed by the United Kingdom for treason during World War I. He worked for the British Foreign Office as a diplomat, becoming known as a humanitarian activist, and later as a poet and Easter Rising leader. Described as the "father of twentieth-century human rights investigations", he was honoured in 1905 for the Casement Report on the Congo Free State and knighted in 1911 for his important investigations of human rights abuses in the rubber industry in Peru.

The Easter Rising, also known as the Easter Rebellion, was an armed insurrection in Ireland during Easter Week in April 1916. The Rising was launched by Irish republicans against British rule in Ireland with the aim of establishing an independent Irish Republic while the United Kingdom was fighting the First World War. It was the most significant uprising in Ireland since the rebellion of 1798 and the first armed conflict of the Irish revolutionary period. Sixteen of the Rising's leaders were executed starting in May 1916. The nature of the executions, and subsequent political developments, ultimately contributed to an increase in popular support for Irish independence.