Ireland held out during a nerve-wracking final quarter in Sydney to ensure their historic season ended with another historic achievement.
A Grand Slam triumph featuring wins in Paris and London was capped by a first series win in Australia since 1979.
Built upon Leinster's European and Pro14-winning squad, Ireland have now won 14 of their last 15 Test matches.
It has been the greatest season in Irish rugby history, but can they better it at the 2019 Rugby World Cup?
The Irish pack mauled CJ Stander over the line in Sydney to give the visitors an eight-point lead at the start of the second half.
But, in the final fixture of a long season, the men in green had to summon a dogged defensive effort for the remainder of the game to deny Australia.
'We've raised the bar'
"I'm looking forward to a bit of a break now. It's been a long 18 months but it's thoroughly worth it," said Ireland and Leinster prop Jack McGrath.
"We've just raised the bar for ourselves in provincial and international so it's all good times and hopefully they keep rolling on."
McGrath and Munster captain Peter O'Mahony both won their 50th Test caps against the Wallabies but neither player could say they are assured of their place in the Irish starting team, which demonstrates the strength in depth that head coach Joe Schmidt has built in his squad.
Both McGrath and O'Mahony had to sit helplessly on the sidelines for the final stages of the game as Marika Koroibete scored a sensational try for Australia and the home side attacked in waves.
Johnny Sexton's late penalty afford the visitors some breathing space before the Wallabies last-gasp attack fizzled out with a loose pass that bounced out of play.
"It was amazing to watch the last 20 minutes. It just shows how far this group has come," added McGrath.
"The belief that is now here to be able to grind it out, I suppose.
"We were under the cosh for the last 20 minutes but were able to fight back and cause them to make a few mistakes.
"We are a bit lucky in some things but you get the bounce of the ball sometimes and it was just one of those things and it's just incredible to be involved in a squad like this, it's a great place to be at the moment."
Attritional, titantic arm-wrestle
Schmidt has a 70% winning ratio as Ireland head coach and has already indicated that he will make a decision on whether to extend his contract before the end of this year.
The New Zealander will be in charge for the World Cup and hopes his team's historic win in Sydney will prepare the players for the challenges they will face in Japan.
"It was attritional, it was titanic and it was an arm-wrestle where there was never going to be much of a margin on the scoreboard at the end of the day," said Schmidt.
"Definitely the second half. I felt with the wave upon wave that came at us, it's hard to keep digging.
"Taniela Tupou is 130kg and he's coming at speed and then [Lukhan] Tui is coming at speed next and the lads did incredibly well to keep them out.
"Some of it is organisation, some of it is knowing the next guy is going to get the next guy and there's a trust element to it and then there's just plain character, throwing yourself under the bus."
The victory in Sydney means Ireland end their season in second place behind New Zealand in the world rankings and five spots ahead of Scotland, their opening opponents in Japan next year.
Schmidt and his players will not entertain speculation about whether or not they can create further history by becoming the first Irish men's team to reach a World Cup semi-final.
But former Ireland head coach Eddie O'Sullivan expects the Six Nations champions to build on their season of success.
"This is the kind of victory that builds character into a team, convinces Ireland that they are definitely number two in the world, practically one year out from the World Cup," said O'Sullivan.
"It will come down to those tight margins but you've got to be there to give yourself a shot.
"This team is definitely good enough to give themselves a shot and then the question is can you take it when you get it, but on that basis you'd have to say that we're right in there.
"Will we do it, we don't know, but we can do it and I think that's what today has proven."