Cunningham played down the significance of the score before the match, but Australia clearly came to Newport with no intention of losing to Wales for the first time, having been victorious in the six previous meetings.
The Wallaroos won a penalty straight off the second-half restart and instead of kicking for touch, Faitala Moleka pointed towards the posts and slotted over.
In contrast, when Wales won a penalty deep in Australia territory, they backed their line-out and kicked to touch.
It was a decision that paid off as Bethan Lewis took clean ball before the pack guided Reardon over the whitewash.
Wales continued to pile on the pressure and a poor clearance kick led to Nel Metcalfe running hard on the counter-attack.
Alisha Joyce-Butchers also made good ground as an impact player and deservedly crossed after Wales' showed good patience in attack.
Games against Australia have always been close affairs, and true to script, Australia hit straight back.
Arabella McKenzie spotted some space behind the Welsh defence and put a kick through for Stewart who then passed inside to Halse, who showed great strength to drive over the line.
It not only marked her 18th birthday, but more importantly got Australia back into the game.
Wales were not done though, they again found themselves with line-out ball deep in Australia’s half, and the driving maul once again proved unstoppable as Reardon crossed for her second.
Australia then threw everything back at Wales in the closing minutes and. despite some desperate defending, the hosts could not keep powerful number eight Tuinakauvadra from crashing over from close range.
Wales then had a chance to seal the win as the clock went into the red.
Lleucu George kicked them to within five metres and the line-out crabbed infield, before several pick and goes finally gave Williams the opportunity to dot down and claim victory.
Wales head coach Ioan Cunningham said: "I was really proud in the way we stayed in the fight, credit to Australia, a great team, scored some nice tries, but we never lost faith.
"We stuck to our systems and had that calmness as well, we've shown a bit of maturity in our team coming off the Six Nations to get that win.
"I thought the lineout went well, we got lots of gain line off that. I thought we grew in the game defensively, which is something we've focussed on over the last two weeks, building that red wall.
"And then that composure and patience which we showed in the second-half when we were close to the try line, we did complete those scores, those are pleasing points for us to build on when we play them next week."
Australia head coach Jo Yapp said: "This week we definitely couldn't fault the girls' work rate and energy, they were working really hard for one another and the intent was there.
"I'm really proud from that perspective, but I think we just showed at times we have just got a few things to learn.
"We need to be a bit more rugby smart in certain areas of the game, I think that's where we let ourselves down tonight.
"We showed that when we executed what we wanted to, we made really good yards against them so we need to continue to build on that and cut out some of the errors."
Image source, Huw Evans Picture Agency
