Treve put in an outstanding performance to win the Prix de l'Arc de Triomphe at Longchamp in Paris.
Jockey Thierry Jarnet, who
replaced the injured Frankie Dettori,
pushed Criquette Head-Maarek's unbeaten filly to a dominant five-length victory.
It was Jarnet's first win in the race since 1994 as Treve emulated Zarkava in 2008 by winning the French Oaks, Prix Vermeille and Arc in the same season.
Favourite Orfevre was second ahead of Intello in Europe's richest horse race.
French racing's number one family, the Heads, have enjoyed many fine days, but surely none greater than this.
As well as Criquette Head-Maarek training Treve, who'll be back in 2014 with an Arc repeat as the plan (what a treat for the sport), the family also bred the horse, with father Alec masterminding it all.
And then Criquette's brother Freddy took the Prix de la Foret with another brilliant filly Moonlight Cloud. What a day.
The Arc result meant, of course, heartbreak for Treve's injured intended rider Frankie Dettori, and more frustration for Japan, finishing second and fourth.
Joshua Tree was the early front runner in the mile-and-a-half race and set a steady pace as Jarnet struggled to get early cover on the three-year-old French filly.
But unbeaten Treve made stealthy progress down the outside and appeared to be in control as she loomed up on the turn for home.
When the pace picked up, the Sheikh Joann Al Thani-owned filly took the lead as Joshua Tree dropped away.
Another burst of speed then sent the winner clear and Jarnet was able to ease up before the line with Orfevre, who
also finished second last year,
Fellow Japanese runner Kizuna was fourth while Penglai Pavilion claimed fifth for Godolphin and Andre Fabre.
Aidan O'Brien fielded two Classic winners in Derby winner Ruler Of The World and St Leger hero Leading Light but neither challenged Treve for the £2.2m winner's prize.
"My English is not good but this is fantastic, magic," said winning rider Jarnet.
Trainer Head-Maarek, who won with Three Troikas in 1979, had sympathy for Dettori after the Italian broke his ankle at Nottingham on Wednesday and was ruled out for the season.
"I send my love to Frankie, he looked after her in the Vermeille because he knew the Arc was the target and I send him a big kiss," she said.
"At one point her head went up in the air and looked bored but she has so much class and is simply a wonder filly that she focussed and was never going to be beaten."