"Heading into that game, we were very much in the land of the unknown. We'd never been in the running for a Grand Slam."

The unknown can be a maker or breaker in sport. Either one rises to the occasion or the opportunity slips.

For the Irish rugby team, St Patrick's Day 2013 was the moment they would face a final frontier of their own and discover whether they could win a first ever Women's Six Nations Grand Slam.

With the benefit of hindsight, we know they would overcome the final hurdle of Italy away in tough conditions.

But tonight at 9.30pm on RTÉ2 and the RTÉ Player, you will be able to relive that historic victory as it unfolded in the latest of our RTÉ Sport Classics.

Someone who will be watching it back for the first time is the star turn of that Irish team Niamh Briggs, as she told our own Darren Frehill. 

"I've not see the game yet. I've never watched it. I look forward to watching it tonight, for sure," the Waterford native admits.

"In my head the rugby was probably way better than what it looked, but I'll enjoy watching it this evening."

The journey for Irish women's rugby was on the cusp of a nice round number that spring, having come 20 years after the first international fixture against Scotland in February 1993.

The weather didn't dampen the celebrations

Up to that point in 2013, silverware had eluded Ireland in the Six Nations. But that all began to change as the steady hand of momentum kicked in.

Led by top point scorer Briggs, Ireland edged Wales away in their opener before overcoming traditional powerhouse England in Ashbourne.

That set the tone as the squad followed that progress up with victories over Scotland and France, setting up the chance to make history in Milan on a calendar date when Ireland is already the focus of global culture.

However, while the sun and fortune would proverbially shine on Ireland at full-time, the weather in Italy was less welcoming pre-match, leaving the team to battle the elements as well as the opposition players. The conditions had the potential to be a game-changing curveball.

"They were the hardest conditions I'd ever played in. The day before, the sun was shining, we were walking around in shorts and t-shirts, sunglasses. The captain's run was really good," Briggs recalls.

"The next morning we woke up, looked out the window and couldn't believe it. The streets were covered in snow, there was kind of sleety rain. It was almost unbelievable."

Briggs kicks the winning penalty against Italy

But Ireland dug in and refused to be daunted. They went down early to an Italian penalty but through Briggs' two accurate ripostes from the boot in each half, a narrow 6-3 result was enough to make history.

"You have to give credit to everybody involved in terms of our ability to change our game-plan so quickly. It was going to be about who could make the least mistakes," says Briggs.

"It made it a little bit more magical that we were able to win a game in those conditions. I wouldn't change it for the world."

The legacy of the victory has gone beyond one day with a further Six Nations title two years later, and vitally, a growth of the game on this island spurred by the inspiration of 2013. 

For Briggs, that is the standout impact of their team's achievement.

"Before that Six Nations not everybody knew Ireland had a women's team, but after everybody knew and that was going to be a huge thing for us. It paved the way for a lot of young girls to be able to play the game and it was an unbelievable thing for us to be able to cherish, that we won the Grand Slam and were able to inspire another generation to play."

Tune into RTÉ2 and the RTÉ Player at 9.30pm to watch back Ireland's historic 2013 Grand Slam clincher against Italy in full.