The Coventry Stakes winner, the 10/11 favourite, started well before Cable Bay moved.
But War Command - ridden by trainer the Aidan O'Brien’s son Joseph - retaliated to win by just over a length from Cable Bay, who was a 20/1 outsider. Outstrip nicked third ahead of Anjaal.
"The ground was plenty slow for him," Joseph O’Brien told Channel4. "When he got to the front he was idling like mad.
"He was waiting for a horse to come to him but did enough. I think he's getting more professional with each race.
"He's definitely a Guineas type. I think he will have no trouble getting a mile and I think the faster the ground, the better he will be."
His father Aidan added: "I'm delighted with the horse as I was very worried about the ground. He's a good-actioned horse and when it was very quick at Ascot,that was what he wanted.
"There is only one Dewhurst and we had to get him out. I'd say he's done for the year now and I think he'll get a mile next season."