President Bill Clinton once lamented that his time in high office denied him the opportunity for greatness, having governed during America’s holiday from history between the end of the Cold War and before the rise of Islamist jihad as a global force. A great president needs to be tested by great events.

The mere existence of war does not make leaders great. The parade of European leaders in the first decades of the 20th century could be judged failures precisely because they permitted the two world wars to arise. It is only after World War II that we look back with admiration at FDR and Churchill and, even then, avert our eyes from the indispensable role of Stalin’s Red Army in overcoming the Axis.