A former Irish soldier has revealed the secret he kept under wraps for 37 years which, had it been known, would have caused a diplomatic incident in the highly-charged days of the Northern Troubles.
Brendan Rohan was a 22-year-old officer when he took part in an unauthorised late-night sortie across the border, which ended with him fighting alongside two RUC constables caught up in an IRA ambush.
Mr Rohan, now aged 59 and living in Co Donegal, said he was finally speaking publicly about the events of December 1974 in order to encourage other people caught up in the Northern Ireland conflict -- soldiers, gardai, police officers, paramilitaries and civilians -- to tell their own stories.
After his cross-border adventures, Brendan retired from the Irish Defence Forces in 1992.
The former soldier now runs a tourism business providing guest accommodation in Co Donegal.
Back when the Troubles were in full flow, Mr Rohan was "a young, idealistic, enthusiastic cavalry officer" who thought he was invulnerable.
While the rest of his unit was preparing for their Christmas party, he left Connolly Barracks in Longford to drive over the Border to Enniskillen to buy new car tyres. On his way, he stopped off at the garda station in Swanlinbar, Co Cavan, and gave a lift to a young detective.
Once in Enniskillen, he dropped the detective off at the RUC station and later called by to pick him up again and was introduced to two police officers who were also heading south.
"On the way back, we were one mile north of the Border when we ran into this ambush. I saw the same two policemen lying in the road firing for all they were worth and I realised I needed to help. It never occurred to me that I was in a different jurisdiction; I just went to help them," he recalled.
Mr Rohan used one of the constables' sub-machine guns to provide covering fire and allowed them to get to the relative safety of a low wall before the IRA attackers fled.
The RUC officers later revealed that they had come across a car parked beside a telephone box with someone inside and stopped to investigate. As one of them approached the box, he saw that it was actually a mannequin and soon came under a hail of gunfire.
A later search of the area conducted by Mr Rohan found a wire stretching across a field where the IRA men had been and leading 20m away to the car by the phonebox. Packed inside was 1,000lb of explosives, which the gang had unsuccessfully tried to detonate.
"I was an hour late for the Christmas dinner and my boss was furious. The next day, he paraded me and demanded to know what had happened. I told him my car had broken down but he didn't believe me," said Mr Rohan.
"In 1974 the political situation was quite different in Ireland. Ordinarily we weren't allowed any contact with the Northern Ireland security forces."
Mr Rohan knew that a soldier from the Republic opening fire in Northern Ireland would have caused huge embarrassment for both the Irish Defence Forces and the Irish government so he remained silent -- until now.
He decided to finally speak about that remarkable night after taking part in a memoir competition run by RTE Radio 1's 'The John Murray Show' and said he now hopes others will share their memories of the Northern Ireland conflict.