A rare original copy of the 1916 Proclamation could fetch up to €350,000 when it goes under the hammer this month.
The edition was owned by Rory O’Connor, who led an occupation of the Four Courts in Dublin in 1922 in protest at the newly formed pro-Treaty government.
The Adam’s auction will also include a telegram sent from the top army commander to his troops following the assassination of Michael Collins, urging there be no violent reprisals.
Director of Adam's Stuart Cole said the Proclamation was the highlight of the Independence sale, now in its fourth year.
“To find copies of the Proclamation are pretty rare and proclamations which have a natural association with people involved in the events are incredibly rare,” said.
Rory O’Connor formed part of the GPO garrison in 1916 but is more famously known for leading an anti-Treaty force which took over the Four Courts in Dublin in April 1922.
O’Connor surrendered after Michael Collins shelled the complex in June.
As the Civil War raged, O’Connor was executed in December in reprisal for the killing of Dáil deputy Sean Hales.
The Independence auction will mark the first time the unsigned Proclamation, which is said to be in relatively good condition, has been put up for sale, as it had remained within the O’Connor family.
There are around 600 lots being auctioned in the sale estimated to be worth almost €1 million in total, including documents and medals.
Another highlight is a telegram sent in August 1922 from General Richard Mulcahy, Commander in Chief of the Irish army, to General Emmet Dalton urging troops not to retaliate for the killing of Michael Collins.
The top commander urged his men to “stand calmly to your posts” and “let no cruel act of reprisal blemish your bright honour”.
It’s estimated to fetch between €15,000 euro and €20,000 euro.
The Independence sale will be held on April 28th in Dublin.
Last year an original signed version of the Proclamation of Independence fetched a record-breaking €360,000.
The document, which was in good original condition and signed by rebel leader and bodyguard to Tom Clarke, Sean McGarry, was purchased by a private Irish collector who wished to remain anonymous.
Separately today, the grandson of James Connolly and Molly O’Reilly’s niece will re-enact the hoisting of the Citizen Army flag at Liberty Hall in Dublin at midday.
The North Inner City Folklore Project is holding a pageant to honour the men and women of 1916-1923.
Relatives of families who took part in the 1916 Rising will be present for the parade to the GPO, where wreaths will be laid at 1pm.
The Proclamation will be read by Noirín Byrne, who will also call for the erection of a permanent memorial in O’Connell Street to the women of the rebellion.
PA