Roger Casement was born on 1 September 1864 in Sandycove, County Dublin, but moved in 1873, after the deaths of his parents, to live in County Antrim. His first employment was with a Liverpool based shipping line, but he soon became disillusioned with this and joined a group of volunteers working with Henry Stanley in the Congo in 1884. He later joined the British Foreign Service and in 1895 was appointed consul of Lourenco Marques in Portugese East Africa; then spent several years working in Africa and Putamayo, South America, earning a reputation for exposing the poor conditions under which the indigenous population was forced to work.

He was knighted in 1911, and returning to Ireland in 1913, he retired and became involved in Irish nationalism. In November 1913 he joined the Provisional Committee of the Irish Volunteers, actively recruited for the organisation and became convinced of the need for it to be armed. He was heavily involved in raising funds for this in Ireland and London and on 2 July 1914 he left for America to raise support among Irish Americans.

The outbreak of the First World War caused Casement to rethink his plans. His sympathies were with Germany and he was convinced that England's aim was to extend her empire rather than to help small nations such as Belgium. John Devoy's opinion was that supporters of Clan na Gael in Ireland were prepared to raise a rebellion but lacked arms and trained officers. Casement became convinced that, if Germany were to aid the rebels, it would be to their mutual advantage in diverting British troops from the continent to Ireland. After an encouraging meeting with Franz von Papen, the German military attaché in Washington, at which they discussed the possibility of Irish prisoners of war being persuaded to change allegiance, Casement decided to sail for Germany on 14 October 1914.

His route took him and his companion, Adler Christensen, a young Norwegian Casement had met in New York, via Christiania (now Oslo), Norway, where began a series of attempts by the British to use Christensen to capture Casement. This culminated in a written promise by Mansfeldt de Findlay to pay Christensen £5,000 in the event of Casement being captured as a result of information given by him [P127/1].

Casement's first two months in Germany were promising and led to an official German declaration of support for the Irish cause [P127/4], as well as a secret agreement concerning the aims of an Irish Brigade [P128/2]. Captured Irish troops in Germany were moved to a special camp at Limburg, near Frankfurt, for the purpose of forming them into a brigade, with the ultimate aim of landing them in Ireland with German assistance. The papers show that Casement was well aware of the treasonable nature and possible consequences of his actions [P127/5]. However, attempts to recruit men to the brigade were largely unsuccessful and Casement became increasingly depressed and physically ill. His letters to Captain Hans Boehm [P127/5-9] show his frustration at what he saw as inactivity by the Germans who refused to publish the secret treaty until 200 men had been recruited.

Eventually about 60 men were moved to another camp at Zossen, near Berlin, and a brigade was formed. The papers show that Casement continued to encounter problems; show how dispirited he had become and how he felt he had been abandoned by friends in America [P127/13].

Captain Hans Boehm was assigned by the German High Command to assist Casement while he was in Germany. Casement spoke no German and needed a translator and it was felt that Boehm, who was married to an American and had several Irish friends, would be suitable. The two met in Berlin at the end of February 1915 when Casement was still in the process of trying to form the brigade from the men at Limburg. The papers show how much, from this point, Casement came to rely on Boehm to help form the brigade [P127/6-8]. They continued to meet and correspond until Boehm was sent away (possibly to America) in September 1915 [P127/11, 14-16]. It is possible that Boehm was also used by the German authorities to deal with separatist groups in Italy. Early in 1917 he was arrested in British waters off Falmouth and interned.

The letters in the collection continue until December 1915. Casement was very ill during the Spring of 1916 and when he heard of the proposed Easter Rising he decided to go to Ireland with only two brigade members, Robert Monteith and David Bailey. They landed at Tralee Bay, County Kerry on 21 April 1916 where Casement was arrested. He was taken to London, tried, found guilty of treason and executed on 3 August 1916.