After a successful emergency sealift from a beachhead at Dunkirk, these British and French soldiers arrive safely at an unknown British port, in June 1940. (Associated Press)

One of the Aug. 12 Free for All letters about the battle at Dunkirk, “Missing in action: Context,” by Steven Shore, said, “Historians still dispute why the Wehrmacht allowed the Dunkirk pocket to remain open as long as it was.”

As explained in the definitive “Hitler’s Generals” (1989), edited by distinguished historian Correlli Barnett, German dictator Adolf Hitler issued “an order to halt the armour’s advance and leave it to the Luftwaffe to finish off the enemy.” This statement is footnoted to Colonel-General Franz Halder’s war diary, published in 1962. He and other German generals had explained this situation to senior Allied prisoners shortly after Dunkirk and to Allied interrogators immediately after World War II.

The reason: After the German ground forces’ smashing successes against the French and British armies in May 1940, German air force commander Hermann Goering had demanded that his Luftwaffe be allowed to destroy the remnants of those armies. His aircraft did exact a frightful toll on men and the evacuation ships and craft in their air attacks, but failed in their effort to annihilate those troops.

Norman Polmar, Alexandria