Emmanuel Macron's victory in the French presidential election averted a crisis for the European Union. Had she prevailed in Sunday's vote, Marine Le Pen could have helped set the bloc's demise in motion, even if her most radical proposals, such as holding a referendum France's eurozone membership, would have been difficult to implement. But though France's election marked another defeat for Euroskeptic forces, the country's political challenges -- and, by extension, those of the European Union -- are far from over. The next French president will have several important domestic and foreign policy issues to manage, chief among them the country's crucial alliance with Germany....