It was a simple plan. Hardly original, but boosted by the new enthusiasm for Europe that a young, newly elected French president brought to the cause. France would work with Germany to reform and strengthen the eurozone, make it crisis-proof. Others would soon rally around the new Franco-German alliance. Prosperity was around the corner.

Emmanuel Macron, the novice politician elected to the French presidency in May 2017 after a strong, unabashedly pro-European campaign, saw eurozone reform as the cornerstone of his diplomacy.