Call it one of the biggest turnarounds in the US Federal Reserve’s storied history. With Jerome Powell concluding his two-term tenure as Fed chair on 15 May, his legacy is likely to reflect a striking irony - it will have been secured by the man who sought most aggressively to undermine him.

History is often written in the shadows of conflict, and Powell’s leadership at the Fed is no exception. The narrative that will likely endure is not one of multiple failures, but of political resilience. Rather than dwelling on a long list of mishaps - significant policy errors, protracted periods of the Fed ov...