The scars of the conflict in central Africa remain fresh in the minds of those who survived.
The Battle of The Tunnel, on December 16, 1961, in Congo was one of the first foreign UN peacekeeping missions with Irish soldiers.
Far from their training grounds in the Curragh and Glen of Imaal, members of A Company (Dublin), supported by B Company and C Company (Tipperary, Limerick, Cork), 36th Infantry Battalion, dug into the African soil to defend themselves from sustained gunfire and mortar shelling from mercenaries and the Katanga Gendarmerie during a civil war.
After nine days stewing in boiling temperatures and torrential downpours, the young men of A Company completed their mission to secure an important railway tunnel to the city of Elisabethville, resulting in a temporary ceasefire.
However, the nine-hour siege outside the Katanga capital left nine casualties, including three on the Irish side: A Company platoon commander Lieutenant Paddy Riordan; Private Andrew Wickham, a signaller from Wexford; and Sergeant Paddy Mulcahy, from Tipperary.
Pte Johnny O'Halloran, from Kilkenny, who was 18, survived a grenade attack on the morning of the planned military assault.
He was part of a supporting B Company contingent that found themselves strapped into a heavy-lifter US Air Force Globemaster military cargo plane that left Dublin Airport on December 6 to a conflict that "none of us knew anything about".
Mr O'Halloran's plane was flying behind another two-storey Globemaster carrying members of A Company that was "hit with enemy fire" but managed to land.
A ground battle ensued for nine days, eventually ending with the bridge being taken by A Company, supported by B Company and C Company.
"The conflict went on for the next eight or nine nights, it was sporadic," Mr O'Halloran (78) recalled.
"They came at us, sometimes at dawn, sometimes at dusk, and there were several near misses, many were injured with shrapnel."
Mr O'Halloran credited B Company's John Holden, now deceased, with playing a key role in removing the threat of the enemy and securing the tunnel. He fired a burst of heavy-artillery shells at it, rendering it safe from Katanga snipers who had been defending it.
"We took cover, but John Holden, from Clonmel, was firing an anti-tank gun that morning and he knocked out a carriage that was strategically placed at the top of the bridge," Mr O'Halloran said. "I believe that is what finished the so-called Battle of the Tunnel, and a few days afterwards there was a ceasefire."
Tony Marshall (78), from Clonmel, said: "By the time we arrived in the Congo, we were under rocket fire, rifle fire and machine gunfire. We could see nothing around us, only rain and fire."
John Griffin, from Sligo, who turned 18 just five days before being dropped into the battle zone and carrying anti-tank shells for Holden to fire at enemy forces, said: "If you were to look back at one day in our lives there was never another one like it since, because we couldn't help but be very much afraid, we couldn't help but wonder if we'd survive.
"There was a huge amount of gunfire, it was chaotic, and we were just young men - teenagers, really."
The first indication their precedence was not appreciated by the locals was when the noise of the engines on the US Airforce two-storey heavy-lifter attracted a volley of bullets as it went to land in country.
Today, they will regroup to reminisce and toast their fallen comrades.
Mr Marshall believes they are "lucky to be around 60 years on".
Mr O'Halloran said: "A few of us who are still left will meet up. We just want to mark it in our own way, and make sure what happened is not forgotten."