Fifty original letters to and from Roger Casement in the three years leading up to his execution have been discovered in the vaults of Clare County Council.
The accidental find was described yesterday by an authority on the Irish patriot, Mr Aengus Mitchell, as "very significant".
The papers had been gathering dust under lock and key in the county council's stores since the late 1960s after being donated to the council by the late Ignatius Houlihan. He had received a gift of the papers from a member of a noble family on the Continent.
The papers, mainly letters, cover the last three years of Casement's life before he was hanged by the British government for his role in the 1916 Rising.
The last letter on file is one from Casement, dated April 4th, 1916, just 11 days before his departure for Ireland on a German U-boat, which landed him on Banna Strand in Kerry on Good Friday, 1916.
Council archivist, Ms Róisín Berry, said yesterday she discovered the papers when she was doing an inventory of the council's archives. "At first, I did a double take. I wasn't expecting something so exciting. I instantly recognised the value of them and I was anxious to make them accessible as soon as possible."
Ms Berry said the council intends to put the letters on public display at the Clare County Museum later this year.
The letters date from Casement's arrival in Germany at the outset of the war in 1914 to the month he left on the U-19 bound for Ireland.
They address a range of different subjects, including the enlisting of Irishmen in the first World War, the appointment of an envoy from England to the Vatican, the Findlay affair, the work of Father Crotty in German prison camps, writing articles for the press, keeping a diary, and the desire for peace.
Ms Berry said Casement's concern for the spiritual welfare of Irish prisoners of war in Germany is reflected very clearly in the collection, as is his contempt for the British government and his desire to see it undermined. She said moments of loneliness and paranoia are reflected, as Casement became increasingly isolated from Irish nationalists and the German Foreign Office.
The collection is divided into three sections. The first addresses correspondence between 1913 and 1916 and includes correspondence mostly between Casement and an old German friend from his days in Africa, Count Gebhard Blücher.
Ms Berry said possibly one of the most intriguing documents is a letter from Casement to Countess Blücher which addresses the subject of keeping a diary. "You know the charm of a diary is its simplicity. Its reality and the sense of daily life it conveys to the reader depends not on style, but on truth and sincerity."
Born in Dublin in 1864, Casement achieved fame for his humanitarian work while a British consular official. He resigned in 1913 and devoted the rest of his life to the cause of Irish freedom.