Green Moon, trained by Robert Hickmott and ridden by Brett Prebble, won the Emirates Melbourne Cup at Flemington as the European party largely disappointed with Mount Athos only fifth.
The Marco Botti-trained Jakkalberry fared best of foreign raiders in third, but was some distance away from the accomplished winner.
Green Moon, formerly trained in Berkshire by Harry Dunlop, flashed past the long-time leader Glencadam Gold a furlong and a half from home under an assured Prebble.
Fiorente finished second.
Prebble said: "He was never going to get beat."
The Luca Cumani-trained Mount Athos flew from the rear to finish fifth under Ryan Moore.
Glencadam Gold enjoyed an uncontested lead from the outset, but initiated an admittedly humdrum gallop off which the major European players like last year's respective first and second, Dunaden and Red Cadeaux, had no answers.
Gai Waterhouse's trailblazer fleetingly looked the winner, until the smooth-travelling Green Moon swooped to conquer in the hands of Prebble."It's the pinnacle of racing in Australia," said the winning jockey.
"I've had some great highs here, but you don't get any higher than reaching the pinnacle.
"If he sustained the journey, nothing was going to go with him.
"It's very emotional and it's going to last for a long time."
Nick Williams, son of victorious owner Lloyd Williams, said: "It's terrific. "I'm so proud for all of our team at the farm.
"It's another Melbourne Cup win for 'Team Williams'.
"We've put a lot of money in and a hell of a lot of effort so to get this result is terrific.
"I'm so excited and so happy for all our people."
Botti was proud of Jakkalberry, but was left to rue a lack of pace in the race.
He said: "He ran a very good race, but he probably could have done with the pace being a bit quicker.
"He stayed on very well. It's been a fantastic adventure and I knew I'd left a bit of improvement in the horse.
"I had him at his best today.
"He's got an invitation for the Japan Cup and we can also think about Hong Kong, but we'll see how he comes out of this first.
"There's also Dubai and we'll think about coming back next year."