About 1,100 civilian jobs are to be lost as part of the government's demilitarisation plans in Northern Ireland.
Army bases are being reduced in the plan
The government has also decided to retain only 11 Army bases instead of the 14 originally planned.
St Patrick's Barracks, Ballymena, Shackleton Barracks in Ballykelly and St Lucia in Omagh will close within two years.
The move's in response to the ending of the IRA's campaign announced in 2005.
Armed Forces Minister Adam Ingram gave details of the closures on Wednesday.
He said: "The Ministry of Defence has thoroughly researched the requirements of the future peacetime garrison and taking all factors into consideration - not least efficiency and value for money - has now identified the bases most fit-for-purpose.
"Inevitably, there will be a substantial number of surplus posts as a result of the wider security normalisation programme but every effort will be made to lessen the impact of redundancy with transfer and voluntary retirement."
More than 1,100 civilians who work for the Ministry of Defence will lose their jobs as a result of the closures.
More than 400 people will lose their jobs in the three bases earmarked for closure, while more than 700 will go from other locations.
Military numbers are being reduced in Northern Ireland
DUP leader Ian Paisley said he was very angry at the closures and said he had sought an urgent meeting with Prime Minister Tony Blair.
"This is an absolute disaster," he said.
He said it was a "bad blow" for Ballymena in light of the job losses and was concerned about what would be built on the site.
Sinn Fein assembly member Davy Hyland said: "Anyone with an interest in building a shared future based upon democracy and peace will shed no tears at the removal of this militia from the political landscape."
The SDLP's Dominic Bradley said the move was "long overdue".
He said: "We now have an accountable policing service and democratically controlled policing institutions, so a military presence must belong to the past."
The three additional bases being closed are among the oldest.
The moves are all part of the end of Operation Banner, the Army's support role for the police during the Troubles.
It has been running for 35 years and is the longest operation in British Army history.
It will end on 1 August next year and by then the Army presence in Northern Ireland will have been radically reduced.
At the height of the Troubles there were almost 27,000 troops based in Northern Ireland. By next summer, there will be no more than 5,000.
During the next 12 months, the five remaining watchtowers in south Armagh will also be demolished and the Army will also be withdrawn from most police stations where they still have a presence, including Crossmaglen.
Mahon Road barracks in Portadown, a base for the security forces during the Drumcree standoffs, will be closed by next January.
Other significant bases being closed as part of the process include Bessbrook Mill in south Armagh.