After my tour of the D-Day beaches, I downshifted through small towns and roundabouts—one had some “yellow-vest” protesters—and followed the highway back toward Caen, past stands of trees and signs that warned of a risk of hydroplaning on the flat stretches. Unlike Bayeux, which stands largely intact—the Bayeux Tapestry is a stunner—Caen was bombed to near-oblivion during the war and was rebuilt, not terribly handsomely. From there I took the train back to Paris. It’s so easy now to travel a route that once required a conquering army. Out the window was Normandy—the green fields, the cows, the gray sky, the driving rain.

When I got home, a thick sadness descended, and wouldn’t lift for days. Cemeteries bring back ghosts. But the sadness, or grief, was also world-historical. I kept thinking about the steep cliffs, the wide stretches of beach, the rows and rows and rows of graves. My trip to Normandy had left me with an unsettling feeling that the postwar world—the world of the Marshall Plan and NATO and international alliances that a lot of us grew up believing were unshakable—is fragile. That it may even be over. What has replaced it has not quite taken shape, but it is a world of small leaders and blustery autocrats. I wonder, I truly do, what the veterans of D-Day make of this new world. I will think of them on June 6, and you should, too.