From Defeat in the West, by Milton Shulman (Secker & Warburg, 1947; Dutton, 1948; Arcadia, 2017), Kindle Loc. 199-225:
It is obvious that men make wars. The corollary that men lose wars is a truism that is often forgotten. The popular tendency at the moment is to identify all man’s military achievements with the machine. The aeroplane, the tank, the battleship, radar and the atom bomb amongst others are all credited by various proponents with having been the decisive factor in winning the war for the Allies. It seems to be felt, in some quarters, that given enough aeroplanes, or enough battleships or enough atom bombs, any power could guarantee for itself ultimate victory in a future war. But the story of Germany’s defeat in World War II convincingly destroys such theories.
Germany had sufficient machines to have assured victory for herself more than once during this war, yet she failed. This view has been expressed over and over again by leading military personalities in the Wehrmacht. They propound it every time they talk about Germany’s greatest military mistakes — and each general suggests a different one. Some say it was allowing the British to escape at Dunkirk, others the failure to invade England in 1940, others the refusal to invade Spain and seize Gibraltar, others the attack on Russia, others the failure to push on and take the Suez when Rommel was at El Alamein, others the stupidity at Stalingrad, and still others the disastrous strategy adopted at Normandy. At each of these decisive phases, except perhaps the last, Germany had sufficient material strength to have enabled her to defeat her immediate enemy or to have prevented that enemy from defeating her.
Yet why did the superior power of these machines not prevail? Because the men who controlled them lacked either the courage or the faith or the imagination or the ability to make them prevail. It is a fundamental principle of war that to win battles superiority of machines and men must be brought to bear at the right time and the right place. German strategists failed to carry out this tenet time and time again. Why, then, did these men who guided Germany’s destiny make blunder after blunder until victory became impossible? In the answer to that question, rather than in the quantity and quality of machines, is the real reason for the fall of Germany in World War II.
The causes of the defeat of the Reich were substantially either political or military. The evidence and judgment of the Nuremberg Tribunal has done much to clarify the political reasons behind Germany’s collapse. The military reasons, while obviously subordinate to political events, have not been given the same searching scrutiny and therefore still remain relatively obscure. The discriminating and scientific study of psychologists, sociologists and soldiers will undoubtedly produce the answers. But what evidence have we now on hand to help the historians and students of the future? The men of the Wehrmacht themselves. And their evidence is both interesting and important.
If men make wars, what manner of men were these who led the armed forces of the Reich to its worst defeat in history? What fundamental causes forced the military leaders of Germany to act as they did for five years of war? Why did a group of men with more training, more experience and more passion for the art of warfare than any other contemporary group of similarly trained men fail to ensure the victory that was so often within their reach? It is suggested that at least three weaknesses existed in the framework of the Wehrmacht which combined to produce a defeated, rather than a victorious, Germany. These weaknesses might be summed up in three words — Hitler, discipline and ignorance.