Sunday’s outcome is a huge defeat for the two center-right and center-left groupings that have dominated French politics for 60 years, and also reduces the prospect of an anti-establishment shock on the scale of Britain’s vote last June to quit the European Union and the election of Donald Trump as U.S. president.In a victory speech, Macron told supporters of his fledgling En Marche! (Onwards!) movement: “In one year, we have changed the face of French politics.” He went on to say he would bring in new faces and talent to transform a stale political system if elected.

Conceding defeat even before figures from the count came in, rival conservative and Socialist candidates urged their supporters now to put their energies into backing Macron and stopping any chance of a second-round …