Take in the celebrations of the Boys in Green, the tears of those in red, the sheer concentration and determination showed by the Republic’s heroic players and you’ll be halfway to understanding why the World Cup continues to mean so much, certainly outside of London.
It was never possible for both these teams to finish the night happy but nevertheless it was not only tension and apprehension which filled the Welsh air but also raw passion, overflowing pride and a sheer determination to make something special happen on the pitch. And so it did as Martin O’Neill’s boys clinched a play-off place with a classic away performance.
Just listening to the pre-match national anthems sent a shiver down the spine and left nobody, anywhere around the world, in any doubt that reaching the World Cup Finals meant everything to these two countries.
What a contrast to those strange and eery scenes at Wembley just five days ago when England booked a place in Russia with a 1-0 victory over Slovenia to almost total silence. Perhaps a lack of tension was part of the problem as Gareth Southgate’s side, always favourites to finish top of their group, were said to ‘limp into the World Cup Finals’ - but that would be ignoring so much of the problem which dogs international football across the water.
The chasm between England’s expectation and reality, the gulf between their team and their fans just seems to get wider every year and now apathy has overtaken empathy.
Not so for the Republic, not so for Wales.
Chris Coleman’s team, along with Iceland, were the biggest story of Euro 2016 while the Boys in Green were unanimously voted the biggest heroes of the tournament off the pitch in France (and in fairness the Welsh crowd could not have been far behind).
The key is that Wales and the Welsh are together, Ireland and the Irish are together – and although they sometimes travel more in hope than expectation their teams and fans never fail to understand the importance of the opportunity.
How the Irish hordes took that mantra to heart in Cardiff, roaring their side on from beginning to end in what was a pulsating atmosphere that would have done any cup final proud and wouldn’t have seemed out of place in a Six Nations decider.
On the pitch there were heroes everywhere, too. Not a lot of quality, the England crowd might have complained, not a lot of entertainment, not many clever flicks or extended spells of possession – but there was no end of brave, concentrated and disciplined performances from Randolph to Duffy, Ward to Arter, Hendrick to McClean. The kind of football, the kind of attitude, to make a nation proud. The kind of heart, in fact, which was typified by captain David Meyler who had such a tight grip on midfield, even more so after Joe Allen went off injured, that Ireland never really looked in trouble in a textbook away performance.
Arter, in fact, called it in a pre-match interview in which he discussed the Irish character, saying: “When we’ve needed to do it we’ve done it, we’ve stepped up. You back to Germany at home when nobody expected us to do anything but we came up with a famous win. Against Italy in the Euros the same. This group rises to the big occasion.” No-one typifies that character more than McClean, who has now scored in four consecutive competition away internationals – a man who produces when the going gets tough and whose sumptuous finish was one of the real moments of quality on a night when organisation and discipline were more common watch words.
It wasn’t that Wales played particularly badly, but without injured Gareth Bale to break the deadlock Coleman’s team, which reached the quarter-finals in France, could not rise to the occasion in the same way the visitors did.
In the end, the better team, the team which was most together, most organised and most determined, did the job.
That’s what international football should be about – and of course the celebrations both on and off the pitch which proved what a play-off tie means to everyone in green. There were no empty stands for the lap of honour here - not for either team - and Russia will be a better tournament, a better occasion, if the Republic can go one step further and join England there.