IT was a process shrouded in secrecy and the destruction of weapons first by the Provisional IRA, and later loyalist paramilitaries and smaller republican groups, was essential to sealing the peace.
But the finer details of how and where those groups disposed of their weapons has never fully been told.
The Provisional IRA's arms were believed to have been placed in underground caskets and rendered unusable in a process ending with an historic statement by Canadian General John de Chastelain in September 2005.
It would be almost five years later, just as legislation allowing for the decommissioning process was about to expire, that several smaller organisations announced they too had handed over their weapons.
In 1995, some former Official IRA members were involved in the launch of the Official Republican Movement (ORM) and decommissioning was overseen by this wing of the organisation in February 2010.
It made the announcement on the same day that the INLA confirmed it had decommissioned its arms.
The Official IRA had been behind the murders of around 50 people, mainly in the early 1970s.
Now for the first time an insider has revealed details of what happened during the decommissioning process, what brought the groups to that point and why the republicans continued to re-arm long after a ceasefire declared in 1972.
Speaking to The Irish News, a senior member told how collecting the organisation's weapons presented many challenges, not least the length of time many of the guns had been stored.
"It was in the dead of the winter when the process started so there were challenges there when it came to accessing remote locations," the source said.
"The weapons were collected from four main areas. On one the trips I was in the front of a 4x4 with the boot and back seat loaded full of guns, it was quite surreal."
The Independent International Commission on Decommissioning, set up in 1997 to facilitate the process following an agreement between the British and Irish governments, provided certificates for immunity from prosecution for those involved in the collection and delivery of weapons.
These protected those involved in the event that they might be stopped and searched during the process.
The Irish News has seen the documentation which until now has remained confidential.
Signed by commissioners General John de Chastelain, Brigadier-General Tauno Nieminen and Andrew D Sens, it stated: "The above mentioned persons will have full authority over the conduct of search, collection, possession and movement of arms.
"The commission requests that the holders of this document be given every assistance, and not hindered in the performance of the movement of arms which are the subject of this document.
"The movement specified in this document is being made with the intention of decommissioning at the earliest opportunity all material collected under this authorisation."
One of those involved in the decommissioning for the Official IRA said: "It's a strange feeling driving a car full of weapons and knowing you have immunity.
"It did feel historic at the time."
The OIRA weapons were taken to a location close to the border - the organisation had always maintained a presence in Newry.
There were no explosives but there were Russian rifles and silencers dated from the late 1980s, long after it had called a ceasefire.
The OIRA's links to Soviet communists is well documented, with many of the newer weapons having come from arms routes established though those contacts.
The source said they were first approached by Finish army general Tauno Nieminen, who opened a dialogue with them about handing over weapons.
With the deadline for decommissioning approaching before legislation expired, this resulted in members having conversations about the guns they had retained and whether it was still justified in keeping them.
"We never recruited, so our members are all of a certain age. The memory of the feuds with the Provisionals and the INLA remained vivid in many.
"Those weapons were retained for protection of our members who vowed they would never be in that vulnerable position ever again.
"But by 2009/10 that was no longer a consideration. Sinn Féin were very much part of the establishment by then and there was no threat.
"Our members were all older and in a politically reflective mood and so it seemed the right thing to do."
It is thought the weapons were taken to a lock-up garage close to the border and then destroyed by Irish army personnel in the presence of members of the commission and appointed OIRA members.
There has been speculation that the organisation had a stash of so called 'doomsday' weapons, kept for the eventuality of a civil war, sourced through Soviet contacts.
While the senior OIRA member dismissed this, he did say that some new, never-used weaponry wasn't traced in time for the handover.
"People had weapons, not huge quantities, but there were some guns kept with a specific person who died and they've never been found and I doubt ever will be.
"For our part everything within our reach and in our possession was handed over."
