The Connaught Rangers was one of six lost Irish regiments in the British Army, disbanded with partition in 1922 and largely forgotten by history.
The Rangers were formed during the Napoleonic Wars, recruiting men from the west of Ireland.
But many Northerners joined the unit at the outbreak of the First World War, when the Rangers made helped popularise 'It's A Long Way To Tipperary' by making it their marching song.
The Rangers - 'The Devil's Own' - suffered horrific casualties during the war, but also collected 42 battle honours, including a Victoria Cross at the Battle of the Somme.
Part of the regiment famously mutinied in India in 1920 over the actions of the Black and Tans back in Ireland. One of the ringleaders was the last man executed by the British Army for mutiny.
North Belfast man Robert McKillen, whose great uncle joined the Rangers in Belfast in 1914, said the end of the Troubles has helped people speak openly about Irish involvement in the First World War.
"One of my interests in retirement is in reviving the history of the Connaught Rangers," he said. "These were men who gave their lives not just for people here but for the people of Europe.
"I think that has been forgotten. What we don't remember is these young lads were promised Ireland would get independence if they went off and fought.
"There was a lot of bitterness towards them when that didn't happen, and even to this day people don't want to talk about it in some places.
"The community as a whole has been a bit late in recognising the sacrifice that was made, but the interest is growing and people are starting to recognise what they did."
Mr McKillen said the 6th Connaught Rangers - the battalion was virtually wiped out in 1918 - was "mostly recruited in west Belfast, where there was a big pool of unemployed people".
His great uncle, Patrick McKillen, was among the recruits sent to France in 1915. He received a commendation for manning a machine gun post for 24 hours, but was killed in August 1917 at the battle of Passchendaele.
"He worked in Ross' Mill before the war and he was engaged to a girl, Mary McCann of Dunmore Street," he said. "She never married and kept a photograph of him beside her bed until the day she died in her 80s.
"I went over last year and put flowers on his grave. It's surprising how many other people have done it."
The regiment was formally disbanded in 1922, along with the Royal Irish Regiment, Leinster Regiment, Royal Munster Fusiliers, Royal Dublin Fusiliers and South Irish Horse.