AP Photo

BACK IN November 2011, as Europe struggled with its ongoing financial crisis, Polish foreign minister, Radek Sikorski, gave a speech in Berlin that beckoned toward his country’s western neighbor and pleaded with it to save the euro. “You know full well that nobody else can do it,” said Sikorski. “I will probably be the first Polish foreign minister in history to say so, but here it is: I fear German power less than I am beginning to fear German inactivity. You have become Europe’s indispensable nation.”

Indispensable? This was an extraordinary statement from a top official of a nation that was ravaged by Germany during World War II. And it reflects a profound shift taking place throughout Germany and Europe about Berlin’s...