Daniel Coyle was first into the ring aboard Farrel and delivered exactly what the packed Irish grandstands had been waiting for: a fault-free round, greeted by an incredible ovation. Great Britain’s Robert Whitaker and Equine America Vermento left every fence standing but picked up a single time penalty, before Janika Sprunger and Orelie added a clear for Switzerland.

Germany endured a more difficult start as Andre Thieme and Paule S finished on eight faults, while the Netherlands’ Roel Holthuizen and Carlson W3 collected four faults and one time penalty. Fresh from his victory in Thursday’s Cashel Palace Hotel Stakes, Karl Cook continued his excellent week, this time aboard Caracole de la Roque, producing a clear round for the United States.

Belgium and France began their campaigns on four faults through Nicola Philippaerts and Gadget Mouche and Olivier Robert and Iglesias D.V., respectively.

The atmosphere continued to build when Jordan Coyle, already a winner twice in Dublin this week including Wednesday’s Sport Ireland Classic, entered the arena with Chaccolino. Another clear round brought the crowd to its feet and kept Ireland on a perfect score. Germany’s René Dittmer and the Netherlands’ Lisa Nooren also delivered important clears for their teams.

But the biggest reaction was still to come. Shane Sweetnam and Coriaan van Klapscheut Z produced Ireland’s third clear round, sparking an explosion of celebration from the home crowd. With three fault-free scores already secured, Cian O’Connor did not need to start in the opening round, allowing Kentucky TN to remain fresh for what promised to be a decisive second round.

At the halfway stage, Ireland and the United States were tied on zero faults, with Great Britain sitting third on two faults, ahead of Switzerland on four. With the second round contested in reverse order, everything remained open.

A thrilling battle to the final rider

France was first to return, with Olivier Robert and Iglesias D.V. opening the second round. It proved a difficult return for the French combination, who finished on 12 faults. Roel Holthuizen followed for the Netherlands with eight faults, while rails also fell for Nicola Philippaerts and Janika Sprunger as the pressure began to build.

It was Karl Cook and Caracole de la Roque who produced the first double clear of the afternoon, keeping the United States firmly in contention. Ireland immediately answered through Daniel Coyle and Farrel, who delivered another fault-free performance to an enormous reception from the home crowd.

The contest between the two leading nations intensified when Paris Sellon and Chad Blue PS added another clear for the United States. Ireland could not afford a mistake, but Jordan Coyle and Chaccolino responded in perfect fashion, completing their second clear and sending the Dublin grandstands into celebration once again.

Germany, meanwhile, produced an impressive comeback in the second round. Andre Thieme and Paule S, René Dittmer and Cody 139, and Jörne Sprehe and Toys all jumped clear, allowing the German team to recover strongly after a more difficult opening round.

With the competition reaching its climax, the question was clear: would the United States or Ireland claim the historic 100th edition of the Nations’ Cup of Ireland?

A rail for Natalie Dean and Mr Boombastic gave Ireland an opportunity, but Shane Sweetnam and Coriaan van Klapscheut Z also finished on four faults, leaving the two nations locked in a tense battle ahead of their final riders.

Elsewhere, Great Britain added eight faults in the second round and slipped to fifth, while Switzerland moved into podium contention, eventually securing third place.

Then came the decisive moments. Laura Kraut and Baloutinue entered the arena for the United States and delivered a crucial clear round, putting all the pressure on Ireland’s final combination, Cian O’Connor and Kentucky TN.

With the packed RDS holding its breath, O’Connor needed a clear to keep Ireland’s hopes alive and force a jump-off. The Irish combination negotiated the opening part of the course, but a rail in the middle of the triple combination finally settled the contest.

The United States had won the 100th Nations’ Cup of Ireland for the Aga Khan Trophy.

After two amazing rounds of competition, the United States claimed victory on zero faults, with Ireland finishing second on four faults and Switzerland completing the podium on eight faults.

A century after the Nations’ Cup of Ireland began its remarkable history, packed grandstands, glorious sunshine, world-class sport and a contest decided by the final rider provided a fitting celebration of one of international show jumping’s most prestigious team competitions.