Trainer Aidan O'Brien won his ninth Irish 1000 Guineas courtesy of Peaceful, who helped Galileo bag a record 85th Group One victory as a stallion.
The 3/1 chance hit the front outside of the furlong marker and established a handy lead in a race which developed into something of a sprint. He was always in command thereafter and won with plenty to spare.
Favourite Albigna was a shade disappointing as the winning trainer's son, Donnacha, saddled second-placed Fancy Blue, with So Wonderful completing a one-to-three for Coolmore.
The winner had only managed to win one of her three starts last year and was beaten a neck in Listed company at Newmarket on her final start.
However, Heffernan, who had earlier bagged a double on the card, had full confidence is his mount's ability to stay and she was subsequently cut in the market for the Investec Oaks at Epsom, with Betfair offering 11/2 from 14/1.
Fancy Blue made great late progress to give Donnacha O'Brien a great thrill so early in his training career, but 6/5 favourite Albigna never looked comfortable.
"Donnacha loved her in Thurles last year and then she went to Newmarket and couldn't walk a yard in the heavy ground, but still kept fighting and wasn't beaten far at the line," said O'Brien.
"That's the sign of a really good filly, she just wouldn't lie down. She's obviously very good.
"She loves the ground, skipped along, and is very uncomplicated. We always thought she'd stay a lot further than a mile.
"Epsom has to be a possible, the lads will decide, but it has to be a possible for all those fillies.
"We knew he had nice fillies. They are Galileo fillies and we are just so lucky to have them. They are beautifully-bred, big, rangy, scopey fillies and they get better and better."
No rest for Peaceful?
O'Brien revealed next Saturday's Coronation Stakes at Royal Ascot could still be on the cards for the winner and said: "If she came out of it well you'd have to look at it, if the ground was nice there.
"We thought some of these fillies could back up in it. The ground is on the slow side in Ascot at the moment.
"It's rapid the way things are happening this season and it's very hard to make plans because it's changing all the time. You don't get much time to think, but it's just great to be racing.
"So Wonderful ran well to finish third. I don't think she'll get much further. I thought a mile was going to be her limit.
"She's still a maiden so we could always go back and try to win her maiden with her."
