A Portrush-born soldier has become the first British officer to instruct at the Curragh camp since 1922 when Ireland became a Free State.
Lt Col Mark McKinney, 44, spent eight days helping teach human rights and humanitarian law at the Irish Defence Forces' UN training centre.
Lt Col McKinney, who now lives near Perth in Scotland, is a member of the Dundee detachment of the Royal Marines Reserve Scotland. He is in charge of civil and military co-operation.
"I am immensely proud and humbled that a reservist was offered such a positive ground-breaking opportunity," he said.
"I am personally delighted that we have strengthened our already good relationship with the Defence Forces and I am looking forward to a regular exchange of students and instructors on all our courses, which will continue to foster good relations with our NATO and EU allies."
The course also taught negotiation and mediation techniques, working with non-governmental organisations.
Lt Col McKinney spent 17 years as a regular in the Royal Marines and completed five tours there.
He has worked in planning for the UN mission in Liberia where he worked closely with the Defence Forces.
And he maintains that without the efforts of the 90th Infantry Battalion and the Special Operations Task Group provided by the Defence Forces, the mission would almost certainly have failed.
The mission, however, went on to be a complete success and Liberia now has the first ever female president in Africa and enjoys a peace and stability uncommon in the region.
It was the close relationship built up over his seven months in West Africa that later enabled a link to be developed for joint civil/military co-operation training.