The Aga Khan owned and bred Tarnawa, considered one of the finest mares of her generation, has been retired to the paddocks.
Three times a winner at the highest level, the Dermot Weld trained five-year-old attempted to repeat her victory of 12 months ago in the Breeders' Cup Turf last weekend, but finished down the field from a wide draw.
She will be remembered as one of the best mares of recent years and came agonisingly close this season to winning the Prix de l'Arc de Triomphe, one of the very few major Flat races in Europe still to elude Weld.
In typical Weld style she was brought along slowly, failing to win at two, albeit she did pick up black type when second in Listed company.
She was out early at three, winning her maiden in April and adding a Group Three in May. Unplaced in the Oaks at Epsom, the daughter of Shamardal was given a mid-season break before a good end to the campaign, winning another Group Three before adding the Blandford Stakes.
While she was unsuited by soft ground at Ascot on her final start at three, at four she excelled, going unbeaten in four races.
An easy winner of the Give Thanks Stakes first time out, she went on to win the Prix Vermeille, Prix de l'Opera and the Turf at Keeneland.
This year had seen the Arc as her big target, although she did come close in the Irish Champion Stakes, and it looked like Weld was finally going to cross the Paris showpiece off his list until the outsider Torquator Tasso came from behind to win.
She retires having won nine of her 18 races and almost £3,500,000 in prize-money.
Pat Downes, manager of the Aga Khan's studs in Ireland, said: "She got back on Wednesday and we'd had a chat since the race on Saturday, we decided it was time to retire her now and welcome her to the broodmare brand.
"She's been an absolute star over four seasons. She has been so consistent and seldom let us down when she raced. This year, I suppose, was a bit frustrating - but in defeat she has run some tremendous races and the Arc maybe took a bit more out of her than we might have realised.
"Going to Del Mar, coupled with the trip over there, just might have taken the edge off her. But she has been a tremendous mare for us.
"I suppose last year's Breeders' Cup would be a highlight, but going to France and winning the two Group Ones was a highlight as well.
"She didn't win her first Group One until last year but, as a three-year-old, she won Group Threes and a Group Two and was such a consistent filly. It was a great pleasure mapping out a campaign for her.
"She was one of those fillies that rarely ever let us down, and they are rare."
Tarnawa will return to Gilltown Stud in Kilcullen, County Kildare, and Downes added: "It's exciting. We look forward to judging who she might visit.
"Those discussions will take place in the coming weeks and we will see where we end up."