After pop star Anne-Marie’s frenetic pre-match show, England fluffed their own first lines, failing to catch the kick-off.
That, combined with a scrappy exit, allowed the United States an early spell of possession.
Ilona Maher, whose social media fame has spread word about the game and propelled this tournament to a new audience, made a brief indent on an inside line, but otherwise England’s defence forced the visitors into retreat.
The contrast when the Red Roses got hold of the ball was stark.
Breach hit a line, Zoe Harrison dabbed a kick in behind and Abby Dow chased like fury.
England made metres hand over fist and, that intensity, combined with set-piece dominance, made a breakthrough inevitable.
It came via a familiar route.
England’s last line-out in World Cup rugby had been stolen by New Zealand in a dramatic conclusion to the final three years ago, but the driving maul remains a potent weapon and flanker Sadia Kabeya was decisive as England fired up the steamroller once more.
The United States were similarly overpowered at the scrum, conceding three penalties in the opening 20 minutes.
Their opponents’ lack of platform gave England freedom to experiment and a precise Megan Jones cross-kick created their second try, Dow chasing, scrapping and gathering, before Hannah Botterman rampaged between two tacklers and swatted aside full-back Lotte Sharp to score.
The United States shot back as second row Erica Jarrell-Searcy shrugged off Breach in midfield and showed superb pace to scamper in.
With their lead cut to 14-7, England could have got twitchy, but any opening-night nerves were eased as United States centre Alev Kelter, who plays her club rugby with Loughborough Lightning, was shown yellow a minute after Jarrell-Searcy’s score.
Kelter’s impulsive slap of the ball out of scrum-half Natasha Hunt’s hands proved costly.
During Kelter’s 10-minute stint in the sin-bin, Maud Muir shunted over from close range before Kildunne crossed at the end of a sweeping coast-to-coast move.
With Harrison kicking superbly off the floor, the scoreboard ticked to 28-7 by the break and any scent of an upset had disappeared.