The Queen has awarded the Royal Irish Regiment the Conspicuous Gallantry Cross at a ceremony in Belfast.
The Queen attended the RIR march at Balmoral in Belfast
The parade at the Balmoral Showgrounds was held to mark the disbandment of the regiment's three home service battalions.
Several thousand members of the regiment, and its predecessor the UDR, attended the ceremony.
"Your contribution to peace and stability in Northern Ireland is unique," she said.
The Queen said the regiment "had never flinched despite suffering extreme personal intimidation".
"Today you have cause to reflect on the fine achievements, while remembering the suffering," she added.
The three home service battalions of the Royal Irish Regiment will be disbanded next July.
More than 60,000 men and women have served in the RIR or UDR since 1970.
The rain-soaked parade was attended by a range of political figures, current and former members of the regiments, disabled veterans and relatives of many of the 274 soldiers killed by the IRA and other republican paramilitaries.
Some 300 home service soldiers drawn from the Holywood-based 2nd Battalion, the Armagh-based 3rd Battalion, and the Omagh-based 4th Battalion took part in the ceremony at the showgrounds.
They were accompanied by musicians from the band of the Royal Irish Regiment and 100 former UDR soldiers of the Regimental Association.
The Duke of York, the RIR's colonel-in-chief, also attended the ceremony.
Guests included Secretary of State Peter Hain, Church of Ireland Primate Lord Eames, DUP leader Ian Paisley, UUP peer Lord Trimble and Ulster Unionist leader Sir Reg Empey.
Among those who met the Queen were SDLP deputy and South Belfast MP Alasdair McDonnell, and party colleague Pat McCarthy, the city's lord mayor.
However, they did not attend the subsequent ceremony.
The home service battalions are being disbanded because of the end of Operation Banner, which is what the Army called its support role for the police during the Troubles.
The Conspicuous Gallantry Cross was received by Corporal Claire Withers, whose father - Corporal Trelford Withers - was the last serving RIR soldier to be killed by terrorist action.
It is the first time the medal - second only to the Victoria Cross - has been awarded to a military unit rather than an individual serviceman.
Trelford Withers, 46, was shot dead on 8 August 1994 as he worked in his butcher's shop in Crossgar, County Down.
Claire Withers, 30, said she thought about her father every day.
"I was obviously thinking of him today as well, but I was also thinking of everyone else in the regimental family who has lost a loved one over the years," she said.
Colonel Mark Campbell, who was among those attending, said today's peaceful society could not have been achieved without the RIR's help.
"Today is deeply significant, it is about bringing an honourable and dignified closure to 36 years of continuous operational service," he said.
"During this time, 60,000 men and women - full-time and part-time - served within the Ulster Defence Regiment and the Royal Irish Homes Service.
"Two hundred and seventy four serving and ex-members paid the ultimate sacrifice - and many more carry physical and psychological scars."
The vast majority of the 210 soldiers killed were attacked while they were off-duty, and another 64 were killed after they had left the Army.