Declaration Of War handed Aidan O'Brien yet another major Royal Ascot victory as the bold adventure of Australian-owned Animal Kingdom came to a deeply unsatisfactory end in the Queen Anne Stakes.

It is rare enough for a Kentucky Derby winner to still be running at five, let alone be flown across the Atlantic to appear at this esteemed meeting, but the authoritative performance of Graham Motion's chestnut in the Dubai World Cup saw him sent off the 5-4 favourite back over a mile on grass.

Animal Kingdom pulled furiously in the early stages and emptied out alarmingly as he beat only a couple of stragglers home, while O'Brien's son Joseph had given a beautiful demonstration of patience to produce Declaration Of War to lead shortly before the line.

Billed as a bright prospect before arriving from France last season, the muscular four-year-old had been campaigned quite cautiously and had not exactly sent pulses racing when only fifth when well-backed for last month's Lockinge at Newbury.

O'Brien senior believes Declaration Of War (15-2) was not hard-fit on that occasion and must be ridden to exploit his speed - even venturing afterwards that sprint distances would be far more likely than moving the colt up to a mile and a quarter.

With a sedate pace and a lack of cover clearly hindering Animal Kingdom, Declaration Of War had his own issues to overcome, chiefly with his jockey struggling to find a gap approaching the final furlong.

Eventually it came, and the pair squeezed through, finding the necessary gears to pass Aljamaaheer and Gregorian and take the meeting's curtain-raiser by three-quarters of a length.

Much of the interest, though, was in Animal Kingdom and the atmosphere was somewhat muted afterwards, certainly compared with Frankel 12 months earlier.

Jockey John Velazquez said: "He went up to the start perfectly well and he came out of the gates fine. He was pulling pretty strong and when I let him go, he didn't have it.

"There were no signs early and he was there for me, but he wasn't when I needed him. I'm very disappointed for him."

Animal Kingdom is now bound for Arrowfield Stud in the NSW Hunter Valley.