Wales had won the trophy in Aberdeenshire just 12 months ago, as they retained their title as the best semi-pro side in the British Isles, however, that all ended in Cork as side suffered defeats against Scotland and then England.
Tony Roberts in the Wales goal had to be alert throughout the game with Bray Wanaderes' Barry McGory a threat throughout.
Meanwhile at the other end TNS striker Marc Lloyd-Williams opened his account for his country, latching on to a Graham Evans' throughball and drilling home after just four minutes on the pitch as he came on for Aldershot's injured attacker Chris Giles.
McGory later levelled the score at 1-1 just before half-time, but a major reshuffle during the break paid off for the gaffer.
Evans was replaced by Newport County's Nathan Davies, while in a strange move, Carmarthen keeper Tony Pennock took over from Darren Jones to play in a right-wing back role just ten minutes from time.
Wales' winner came froma nicely worked move down the left flank with former Cardiff City man Damon Searle combining with Carmathen's Gary Lloyd, setting up Merthyr's Jones who condemned Ireland to bottom spot powering home from point-blank range.