Why did the Germans hold off at Dunkirk?

Christopher Nolan's "Dunkirk" is lighting up the box office, with star turns by Mark Rylance and Kenneth Branagh. One set of characters remains largely offstage, however: the Germans, who appear almost entirely in the form of faceless bullets, torpedoes, and bombs.

Yet without the initial German decision to hold back from launching an armored assault on the beachhead, the Second World War might have taken a very different course. The battered British and French troops would have been hard-pressed to turn back any such attack. In its absence, though, more than 330,000 allied soldiers were pulled off the beaches — nearly 10 times the number that the British initially hoped to evacuate. Via e-mail, I asked Robert M. Citino, the author of "The German Way of War: From the Thirty Years War to the Third Reich" and "The Wehrmacht Retreats: Fighting a Lost War, 1943," among others, and the Samuel Zemurray Stone Senior Historian at the National World War II Museum, to shed some light on the Wehrmacht's behavior.

James Gibney: Is there a consensus among historians about why the German military halted outside Dunkirk on May 24?

Rob Citino: No, and there never will be. The entire operational sequence is too complex, even convoluted, and it doesn't help that Adolf Hitler and the Germans themselves were all over the map in explaining it: bad terrain, a desire to let the Luftwaffe alone smash the beachhead, a desire to spare the Panzers, Hitler's desire to cut a deal with the "Aryan" British (this last one is utter nonsense). Both during and after the war, the Germans threw up so much chaff on this question that sorting it out is nearly impossible.

JG: What do you see as the most critical factor?

A: Remember, Hitler's May 24 Haltbefehl ("stop order") did not stop the Panzers from attacking the Dunkirk beachhead. They were already stopped by virtue of a "close-up order" from the commander of the Panzer Group, General Ewald von Kleist, on May 23rd. Kleist's Panzers were badly strung out and worn down as a result of the high-speed chase across northern France. Some of the other army commanders wanted to keep moving forward. The Army Group commander, General Gerd von Rundstedt, backed Kleist, while the Chief of Staff, General Franz Halder, disagreed with Rundstedt, and actually took the Panzer Group out from under his command. It was a mess of the worst sort! When Hitler flew to the front on May 24, it seemed as if the commander he respected the most, Rundstedt, was being sidelined. It also seemed (and this was actually true) that decisions of the highest order were being taken by commanders without looping in Hitler at all — and that was something the Führer was determined to stop. That was the origins of the May 24 "halt order" — an attempt by Hitler to reassert his control over events at the front.

JG: A few days later, Hitler rescinded his decision. What had changed to precipitate that?

JG: How important was the weather to the failure of the Luftwaffe to fulfill Goering's plan to destroy the BEF from the air? Or was Goering merely suffering from what Norman Ohler, in his book "Blitzed: Drugs in the Third Reich," describes as an opium delusion when he made that pledge?

A: Certainly the inclement weather hurt the Luftwaffe during the British evacuation, but that is just another sign of how badly weakened and overtaxed the Luftwaffe was by this point. And Goering didn't need drugs to make foolish promises or boasts. He'd been like that for a long time. I found Norman Ohler's book to be fascinating, but I don't think drugs — or the weather — explain Dunkirk.

JG: As you've pointed out, Hitler's former generals wrote postwar accounts that exculpated their own decisionmaking. But in the immediate aftermath, did the German high command recognize Dunkirk for the missed opportunity it was?

A: They recognized it within days — indeed, while it was happening. Then many of them wrote their memoirs or sat for interviews in which they blamed Hitler for the whole thing. Rundstedt and Kleist were particularly egregious in their revisionism. Yet at the time, both men thought their depleted Panzer forces needed rest and replenishment. Hitler was ultimately responsible, of course, but not solely.

JG: What does the German decision to halt at Dunkirk tell us about what you've called "the curious command hierarchy and decisionmaking mechanisms of the Third Reich"?

JG: Did what happened at Dunkirk between Hitler and his generals have any impact on German decisionmaking going forward?

A: Not really. They had to go through the same ordeal again 18 months later, during the drive on Moscow. By late November 1941, virtually every German field commander in Operation Barbarossa was running a kind of private war, moving in all directions at once in a formless and chaotic mess. The price here would be the great Soviet counteroffensive in front of Moscow in December, which nearly destroyed the German army altogether. Hitler responded this time not by "intervening," but by firing his generals wholesale and even taking over supreme command of the army all by himself. Some people never learn.

JG: And thank God for that. But enough of historical reality. You've just seen the movie. What did you think?

A: It's impressive. "Dunkirk" makes points about the human experience of war — the almost anonymous and randomized killing, the chaos, the confusion — but it also makes a far more directed point about the nature of modern war, the interplay of air/sea/land. And, as a German military historian, I would say that the movie provides the best treatment of a Stuka attack ca. 1940 that I have ever seen.