A blue plaque has been unveiled for the founder of the Gaelic League and the Irish Volunteers Eoin Mac Neill at his old school in Belfast.
Born in Glenarm, Co Antrim, Mac Neill boarded at St Malachy’s College from 1881 to 1887.
Mac Neill's grandson, senator and former tanaiste Michael McDowell, was there to unveil the plaque at the college on Friday, to coincide with the 150th anniversary of the scholar's birth.
Mr McDowell said it was a "great honour and great pleasure" to unveil it.
The ex-Irish government minister said St Malachy's was the "making" of his grandfather.
"He was really very, very fond of this institution and he was somebody who after he ceased to be a pupil here he kept very close ties with St Malachy's," he said.
"There is no doubt that it was the education he received here in St Malachy's which set him on his career and changed Irish history."
Mac Neill would go on to become a law clerk and then history professor at University College Dublin.
Six years after leaving school, he co-founded the Gaelic League with Douglas Hyde. The league was established to promote Irish nationalism through cultural expressions of language and literature.
Mac Neill would later become chief of staff of the Irish Volunteers, the military organisation formed in 1913 to ensure home rule was delivered in Ireland.
When the volunteers split at the outset of the First World War, Mac Neill led the minority faction not prepared to join the British war effort.
But when the clandestine revolutionary body the Irish Republican Brotherhood (IRB) infiltrated the volunteers and plotted to use scheduled manoeuvres on Easter Sunday 1916 as a cover for an insurrection, Mac Neill issued a countermanding order instructing his men to stand down, believing the armed rebellion had no chance of success.
The impact of his order on the Rising, which started a day later with fewer participants than first envisaged, has been a matter of intense historical debate ever since.
After spending a year in prison in the wake of the Rising, Mac Neill went on to play an important role in the subsequent shaping of the Irish Free State.
Paul McBride, principal of St Malachy's, said he was delighted the college was recognising Mac Neill.
"The plaque is located in a very prominent part of the college and will remind present and future generations of students of Eoin Mac Neill's important role in the cultural life of Ireland," he said.
Chairman of the Ulster History Circle, Chris Spurr, said: "As a co-founder of the Gaelic League, Eoin Mac Neill assured his place in his country's history, but he was also an eminent scholar, historian, and linguist.
"The Ulster History Circle are delighted to commemorate Eoin Mac Neill with a blue plaque at the college he attended."
Irish language body Foras na Gaelige helped fund the plaque.