[2] He had two siblings who lived to adulthood, Nell Humphreys and Anno O'Rahilly, both of whom were active in the Irish revolutionary period.

He personally directed the first major arming of the Volunteers, the landing of 900 Mausers at the Howth gun-running on 26 July 1914.

[6][7] O'Rahilly was a wealthy man; the Weekly Irish Times reported after the Easter Rising that he "enjoyed a private income of £900" per annum, plenty of which went to "the cause he espoused".

Learning this, O'Rahilly went to Patrick Pearse's school, Scoil Éanna, on Good Friday.

"[8] Pearse calmed O'Rahilly, assuring him that Hobson was unharmed, and would be released after the Rising began.

O'Rahilly took instructions from MacNeill and spent the night driving throughout the country, informing Volunteer leaders in Cork, Kerry, Tipperary, and Limerick that they were not to mobilise their forces for planned manoeuvres on Sunday.

Arriving home, he learned that the Rising was about to begin in Dublin on the next day, Easter Monday, 24 April 1916.

Despite his efforts to prevent such action (which he felt could only lead to defeat), he set out to Liberty Hall to join Pearse, James Connolly, Thomas MacDonagh, Tom Clarke, Joseph Plunkett, Countess Markievicz, Seán Mac Diarmada, Éamonn Ceannt and their Irish Volunteers and Irish Citizen Army troops.

Arriving in his De Dion-Bouton motorcar, he gave one of the most quoted lines of the rising – "Well, I've helped to wind up the clock -- I might as well hear it strike!"

In a statement to a newspaper reporter, he said that he was taken from the phone box after three hours and brought up to O'Rahilly, who ordered: "I want this officer to watch the safe to see that nothing is touched.

[11] According to ambulance driver Albert Mitchell (in a witness statement more than 30 years later), O'Rahilly still clung to life 19 hours after being severely wounded, long after the surrender had taken place on Saturday afternoon.

I never saw the body again but I was told by different people that it was The O’Rahilly.Desmond Ryan's The Rising maintains that it "was 2.30pm when Miss O'Farrell reached Moore Street, and as she passed Sackville Lane again, she saw O'Rahilly's corpse lying a few yards up the laneway, his feet against a stone stairway in front of a house, his head towards the street".

Permission for the Edwardian era building's demolition was given by An Bord Pleanála, despite calls from various political parties for its preservation on grounds of its connection to The O'Rahilly.

The Department of Culture, Heritage and the Gaeltacht had also earlier voiced its support for the retention of the three adjoining properties for architectural reasons.