From halftime England's innings was all about taking wickets. Keeping the tourists' below the target was never an option, they got in front of the required run rate early, and stayed there.
Morgan clattered three successive boundaries off Trent Boult's sixth over, hooked fast bowler Lockie Ferguson hard for six, and was then dropped in the same over, one handed above his head by wicketkeeper Tom Latham.
The key moment? Morgan, on 40, pulled hard at Tim Southee and Henry Nicholls spilled a difficult catch diving to his left. He had it until his body hit the ground. Stokes rubbed it in by striking back to back fours in the same over.
England got to the target with 73 balls to spare.
New Zealand weren't at the races for much of the first innings, dismissed for 223 in the final over.
Take away a conscientious, if uncharacteristically painstaking half century from Martin Guptill, a brisk 38 from de Grandhomme, a spirited stand of 69 for the eighth wicket between a resurgent Mitchell Santner and tailender Ferguson and you're left with a collection of ordinary decisions on choice of shot and running between the wickets, the latter of which, given the situation, would have earned a bollocking from the school coach.
Santner and Ferguson provided a decent wag in the tail, and how it was needed from a parlous 108-6. Santner chose a good time, his 50th ODI, for his first half century and he squirted, slapped and hoicked effectively, in between some clean, crisp strokemaking.
Four batsmen were run out. Ross Taylor fell to a moment of brilliance from David Willey at backward point, but the losses of de Grandhomme and Southee were dreadful wastes, poorly judged, sluggish running and lack of communication.
England's bowling was immensely impressive. The new ball pair Willey and Chris Woakes were on the job, providing early penetration and a bit of screw tightening; spinners Moeen Ali and Adil Rashid were outstanding, conceding 65 off a combined 120 balls — just five boundaries and 42 singles. Stokes was a strong performer too.
There had been a call for a pick up in the fielding performance and after Willey had taken a fine, awkward catch at square leg, and done his bit with the Taylor run out, Jason Roy chipped in with two excellent catches. His run and dive forward did for Guptill at deep mid wicket, and he followed that with an athletic snare to his right at gully to remove Henry Nicholls.
"We scrapped through to something we could bowl at but it's never easy when you hand the opposition four run outs," acting New Zealand captain Southee said of his team's below-par batting effort tonight.
"The effort from the bowlers was top drawer, to keep coming in trying to create chances. But the way (England) played they were too good today," he said.
Southee felt England had done a good job early with the ball, pegging New Zealand back and preventing a fast start.
"A lot of credit goes to the way England bowled and kept applying pressure and trying to take wickets."
New Zealand won't look at significant changes in strategy or mindset.
"The beauty of this side is we don't get caught up when we're winning and we won't get too down when we're losing. In a couple of days we get to crack on and do it again."
The result ended New Zealand's winning ODI run at nine, one short of the record, set twice, of 10 on the bounce.
Senior batsman Ross Taylor didn't field in England's innings, having strained a quad in unsuccessfully trying to avoid being run out during New Zealand's innings.
England captain Morgan was delighted with the allround quality of their performance.
"We certainly raised our level of intensity," Morgan said.
"Willey and Woakes really did hit their straps in the first 10 overs. Any chances created we certainly put ourselves in a position to take them.
"It was as good a fielding performance as we could have hoped for and that was probably the difference between the teams today."
Former England spinner, now commentator Graeme Swann backed Morgan's delight at the fielding effort, labelling it the best he had seen from an England team.
Game three in what appeals as an even contest is in Wellington on Saturday.
