Declaration Of War ran out a cosy winner of the Diamond Stakes at Dundalk to make it four wins from five starts and a first Group Three success.

Having his third outing for Aidan O'Brien having been unbeaten in two juvenile runs for Jean-Claude Rouget in France, the War Front colt travelled powerfully in mid-division but there was a scare two out as Joseph O'Brien was in behind a wall of horses.

There was no panic, however, and the 11-10 favourite picked up well when switched and asked for his effort.

Stretching out nicely, O'Brien's mount was not asked a serious question in running out a half-length winner over the Pat Smullen-ridden Along Came Casey, with long-time leader Aloof sticking to her guns well to take third.

The three-year-old Declaration Of War holds some big engagements, and O'Brien senior said: "The race was a bit messy, but I'm delighted. He's a horse we've always liked - he travelled well and has plenty of speed.

"I only had him three months before he ran in September. He's a horse that could go a lot of ways. He could turn up in Ascot (20 October) and is entered in the Queen Elizabeth II and Champion Stakes."