For the Taoiseach it was yet another day of remarkable personal sacrifice for peace. All day he sat in the Houses of the Oireachtas, listening to what may have been the largest number of words ever spoken there on one day on the subject of Northern Ireland.
At 10.30 a.m. he sat down in the Dail chamber to respond to the committee stage of the debate on the Bill to amend the Constitution in line with the Northern Ireland Agreement.
At 6.40 p.m. he finally rose from an armchair in the Seanad chamber.
He was given no gentle start to this exquisite test of endurance. From the moment John Bruton rose at 10.30 a.m. he conjured up an appalling vista of constitutional chaos and mayhem that might arise from the proposed changes.
On the bench in front of Mr Bruton sat an open copy of the Constitution, liberally marked by a green highlighter pen. Beside him sat A Dictionary of Irish Law. To his right Mr Jim O'Keeffe ominously held a copy of The First Progress Report of the Constitutional Review Group, with J.M. Kelly's The Irish Constitution sitting in front of him.
As if this wasn't bad enough, Alan Shatter was scribbling notes for Mr Bruton, fingering a very thick book indeed, and had his glasses halfway down the bridge of his nose.
Oh, they meant business all right.
Mr Ahern did not flinch. He responded to all convoluted conundrums, the handwritten notes from his officials piling in front of him.
And when the Bill passed through the Dail at 2.20 p.m., the Taoiseach barely had time to host the normal Question Time before hurrying to the Seanad to guide the Bill through that House before the midnight deadline.
Perhaps it was a small mercy for him that he did not hear the leader of the Seanad, Senator Donie Cassidy, say minutes before he arrived: "On this historic day I'd like to think that the entire 60 senators would contribute."
Mr Ahern entered the chamber to a standing ovation, finished his speech to a standing ovation and then sat to listen. Senator Maurice Manning spoke first, paying tribute to the litany of figures, home and abroad, past and present, who had contributed to the Northern Ireland Agreement.
He warned that it was not yet all over, and that the killing in Portadown the previous night represented the alternative to the agreement. Ireland was now at a crossroads as important as that in 1922 when the Treaty was signed; in 1939 when the State opted to stay out of the second World War; and in 1972 when it decided to join the EEC.
Senator Manning appeared to have said it all, which begged the question as to what the remaining 59 speakers might say. Senator Eddie Haughey, who went next, said frankly: "I risk being repetitive."
In general he was not, but at 5.50 p.m. it finally happened. Mr Ahern, the man who had eyeballed some of the toughest political customers anywhere for weeks on end and not blinked, finally let his eyelids fall shut, just for a few seconds.
Most speakers remarked that it was a historic day. Mr Ahern may have had enough of them for a while.