In 1911 Roger Casement was knighted by King George V for his work exposing abuse of human rights in the Congo Free State. It wouldn't be long, though, till Casement became enemy number one of the British Empire he had once been such a loyal servant to.
Casement was captured and arrested on Good Friday 1916, following an epic journey by submarine, from Germany to Banna Strand in Co Kerry. As a result of Casement's mythological sojourn, with its continual confusion, misinformation, and treachery, a national rising was called off in Ireland.
But with defiance from the IRB, the rebellion on Easter Monday went ahead in Dublin at any rate.
On August 3, after many months of deliberations in the public domain which discussed his clandestine war time activity with the Germans, Casement was hanged for treason at London's Pentonville prison.
Casement's biography is unusually quirky in the pantheon of Irish republican martyrs: he was an aristocratic knight errant; he had a striking conversion from British imperialism to Irish nationalism; he was publicly shamed and discredited before his hanging, due to information that leaked out from the infamous 'Black Diaries': which revealed his appetite for casual sexual encounters with men and teenage boys, on his earlier humanitarian missions as an employee of the British Empire.
These diaries were seen by Irish Republicans, for many years, as forgeries used for propaganda purposes. But it's now almost universally accepted by historians that the diaries revealed the truth.
Despite his involvement in setting up and financing the Irish volunteers, along with Eoin Mac Neill in 1913, and his prominent role in helping to secure a cargo of arms from Germany to Howth Pier in 1914- that would eventually be used in the Easter Rising -Casement always remained outside of the inner circles of the Irish revolutionary movement.
It was this distance, both physically and intellectually, from the revolutionaries, and their secretive ways, back in Dublin, which would eventually prove to be Casement's downfall; subsequently plunging him into a violent depression in the months leading up to his arrest.
In August 1914 Casement visited John Devoy in Philadelphia from the secret society, Clan na Gael: a prominent Irish republican organisation in the United States.
Casement's plan was to seek German assistance, and to recruit Irish prisoners of war fighting in the British army, to return to Ireland and help fight for independence.
Devoy was extremely sceptical of the mission. Still, using his connections with German diplomats, as well as his hefty purse strings, he helped to fund Casement's rather daft military plan.
The mission ended in abysmal failure, and Casement's 'Irish brigade' amounted to a pathetic 56 men.
One Bold Deed of Open Treason: The Berlin Diary of Roger Casement 1914-16 documents these disastrous months spent in imperial Germany, where Casement was, for the most part, severely ill, suffering from nervous exhaustion.
The diary, even today, remains one of the most candid confessions of treason ever scripted by a subject and servant of the British Crown.
When Casement arrived in Germany in late October 1914, his mood was one of healthy optimism.
Pretty quickly, however, his writing began to descend into extreme negativity.
Casement was a highly emotional character, who was often infused with feelings of anger, frustration, self pity, guilt, and inconsistency of thought.
This raw, emotional tone, leaden with a heavy heart, percolates through almost all diary entries from mid 1915 onwards. At other times, Casement's ideas appear to be drastically contradictory.
For example, in December 1914, Casement became so enthralled and enthusiastic about the German temperament of character, that he wrote of his wish to be born German, and not Irish: claiming he felt ashamed to belong to so contemptible a race [as the Irish]." Strange words indeed for a so-called fervent Irish nationalist.
Roy Foster, in his book, Vivid Faces, has argued that, even if this behaviour might seem illogical, it tends to fit "with [Casement's] rather febrile and hero worshipping temperament."
As these diaries progress towards Casement's arrest in April 1916, we begin to witness a man watching his pride, ego, self worth, and reputation, slowly disintegrating before his eyes.
Casement is extremely self aware, when penning these diary entries, that his words will become important historical documents that posterity will study in great detail.
Mythology and martyrdom are two vital ingredients that have held the narrative of modern Irish history tightly together for the last 100 years.
No other figure, however, has acquired the same level of mystique, honour, shame, and curiosity, attached to their name, from both loyal admirers, and most vehement of enemies alike, as Sir Roger Casement has.
Which makes these diaries, especially in the wake of the centenary celebrations - when Irish history is being constantly revised, reassessed, and re-evaluated - all the more compelling and intriguing to read.