Letters written by Proclamation signatory Éamonn Ceannt and by the wife of Joseph Mary Plunkett will be made public for the first time as part of Culture Night on Friday.
The two letters were written to the temporary governor of Kilmainham Gaol Maj William Sherlock Lennon in the aftermath of the Easter Rising.
They have been donated to the State by Sir Charles Knowles, a great-nephew of Maj Lennon.
The letter from Ceannt is dated 11pm, May 7th, 1916 and was written on the night before he was executed.
It is brief and to the point: “To express through him to his subordinates my feelings of gratitude for their kindness and civility during my brief sojourn in their midst.”
The second letter is from Grace Plunkett (née Gifford) who married Plunkett on the night before he was executed. Lennon had given the couple permission to marry.
It is dated Saturday, May 6th, two days after Plunkett was executed. In it she asks for some of Plunkett’s possessions including his hat. She also asks for a letter he wrote to her on the previous Tuesday and for his will. By coincidence both of these documents are in the National Library collection.
A cartoonist, she inquires about some drawings she had done for Irish Life "presumably seized by the military".
She is anxious to visit her sister Helen who was arrested after the Rising having been in the College of Surgeons with the Citizen Army. Grace Plunkett asks, “can food or chocolates or clothes or such things as toothbrushes be sent in?”
The Giffords were from a prominent Dublin unionist family who became radicalised nationalists in the years leading up to the Rising. Another sister, Muriel, married Thomas MacDonagh, like Plunkett, a signatory of the Proclamation.
The letter suggests Grace Plunkett is concerned about how her behaviour will look to her contemporaries. She asks the major: “As many of my intimate friends are prominent unionists – will the fact of my also having many friends among the nationalists and having married Joseph Plunkett cast any suspicion on my unionist friends if I should visit them?”
The letters were presented to the Irish Ambassador to Britain, Dan Mulhall during the summer.
Mr Mulhall, who is also a historian, said: "It was with surprise and huge interest that I first saw the material brought to my attention by Sir Charles Knowles. I immediately recognised its significance and I am delighted that Sir Charles accepted my suggestion that the National Library would be an appropriate Irish institution to which to donate the material.
"I am grateful to Sir Charles for taking this initiative and I know that his generosity will be appreciated by those who visit the National Library to view the Signatories exhibition and by future generations of scholars."
The National Library and National Photographic Archives will be open to visitors from 5pm-11pm on Culture Night.