The surreal atmosphere of the Covid-19 pandemic calls to mind how I felt as a young man in the 84th Infantry Division during the Battle of the Bulge. Now, as in late 1944, there is a sense of inchoate danger, aimed not at any particular person, but striking randomly and with devastation. But there is an important difference between that faraway time and ours. American endurance then was fortified by an ultimate national purpose. Now, in a divided country, efficient and farsighted government is necessary to overcome obstacles unprecedented in magnitude and global scope. Sustaining the public trust is crucial to social...