FORTY YEARS AGO yesterday, at 4:45 a.m., German troops crossed the Polish frontier. Forty years ago tomorrow, at 11 a.m., the British ultimatum to Hitler expired. The greatest and most destructive war in history had begun. Before it was finished it had spread to the ends of the earth, and 17 million soldiers, sailors and airmen and 18 million noncombatants had been killed.

This was Hitler's war. He was able to unleash it with a diplomatic coup which, as one historian has put it, "struck the western capitals like a thunderbolt" -- the conclusion of the pact between Nazi Germany and the Soviet Union. We now know the astonishing rapidity with which it was concluded, the deliberation and evil genius with which he cleared the way for his armies. No one can read even the bare bones of the story and doubt that this man was determined at that moment on general war, even though his public demands all summer were only for the return of Danzig to the Reich and the provision of German access to it across Polish territory.

Here is the record as we now know it from the documents:

April 3: Hitler ordered the Wehrmacht to make a contingency plan in case it should be necessary to destroy Poland's armed forces to occupy Danzig.

June 14: Hitler ordered Army Group III to be ready to attack Poland by Aug. 20.

Aug. 11: Hitler said to Carl Burckhardt, the high commissioner of Danzig: "Everything I undertake is directed against Russia. If the West is too stupid and too blind to comprehend that, I will be forced to come to an understanding with the Russians, to smash the West, and then, after its defeat, to turn against the Soviet Union with my assembled forces."

Mid-August: Count Ciano, the Italian foreign minister, asked Joachim von Ribbentrop, the German foreign minister, what Germany wanted. They were walking in a garden after dinner; Ribbentrop turned to Ciano and said, "We want war!"

Aug. 14: Ribbentrop sent a telegram to the Soviet government, proposing that he should fly to Moscow, "to set forth the fuehrer's views to Herr Stalin."

Aug. 21: German radio announced that Ribbentrop would sign a Nazi-Soviet pact in Moscow.

Aug 22: Hitler summoned his generals and crowed to them: "Now Poland is in the position in which I wanted her . . . I am only afraid that at the last moment some swine or other will submit to me a plan for mediation."

Aug. 23: The signature of the Nazi-Soviet pact.

Within eight days the armies which Hitler had ordered to be ready were driving across Poland, and his Stuka dive-bombers with their first attacks on Warsaw at 6 a.m. told what kind of war it would be.

How can any revisionist say that this was not Hitler's war, and that it did not remain his war, even as Italy and Japan joined him to claim their portions of world empire? Exactly as he had laid out his plans to Burckhardt, he at last turned on Russia as savagely as on Poland, but without fulfilling the essential condition that he had himself stipulated. He did not "smash the West" before he turned east, because he had failed to conquer the tiny island of Britain. There he left it to be the offshore aircraft carrier, as de Gaulle once called it, from which America would lead the West back into Europe.

Yet it is with this monstrous man that there seems today to be an insatiable fascination. For several years on both sides of the Atlantic, the books have been pouring forth, the movies playing to packed audiences, and the memorabilia (cute word) rising in price. How much would now be fetched in New York by one of the lampshades made from human skin?

Whatever the intentions of individuals, the effect is to make the man intriguing, and insidiously to exculpate him. John Toland, one of his American biographers, comes near to presenting us with a Hitler who is really rather like us, but who just happened to be a little more off the tracks and to make mistakes that we avoid.

No professional historian of whom I am aware -- not even a German historian; perhaps one should say, least of all a German one -- has joined in spreading this vicious cult. Not only was the man not like us, he was not even like other Germans. Gordon A. Craig may speak for the historians when he writes in his masterly new book, "Germany 1866-1945," that Hitler was sui generis a force with a historical past, whose very Germanness was spurious because never truly felt," and in the end he repudiated even it. "Both the grandiose barbarism of his political vision and the moral emptiness of his character make it impossible to compare him with any other German leader."

But even this picture, if shallowly read and misunderstood, can feed the cult. One can still feel the force of the man, "self-contained and self-motivated," and so imagine him to have been some kind of superman. The best way to answer the cult is to point out that he was in fact an incompetent.

During the winter of 1941-42, when the fate of his Third Reich might still be said to be in the balance, Franz Halder, the chief of staff of the German Army, complained in these words: "The ever-present underestimation of enemy capabilities is gradually assuming grotesque forms. One cannot any longer speak of serious work. Cranky reactions to the impressions of the moment and complete lack of the command organization and its capacities give this 'leadership' its characteristic stamp."

It was not only his military judgments that were at fault. He was forever meddling with his administration and placing the mediocre and the erratic above the trained and the experienced, always setting the dogs of his party at the throats of not only generals but ministers who made the mistake of offering him realistic advice. We know the economic mess that Albert Speer was expected, much too late, to convert into an efficient war machine. But from start to finish, Hitler was never ready to put the economy on a war footing. His disastrous as well as inhumane policy of relying on forced labor from the countries that he subjugated was a direct result of his unwillingness to mobilize the German civilian population to the full.

As a dictator he was never sure of his support among the German people. Elaborate surveys were always being taken of their mood. He could ask obedience but did not ask real sacrifice on the home front, while Churchill was unable to ask obedience of his democracy but did ask great sacrifice. America organized for total war more efficiently and completely in a year than Hitler did in all his 12 years.

So what did he have? He had what Craig calls "an indomitable will and self-confidence." Field Marshal Fritz von Mannstein once said of him that he was always "so confident that his force of will would be able to surmount any difficulty that he forgot that the enemy possessed will too." But it is precisely this force of will which I suspect is now attractive. This is what fuels the cult.

Let me be clear why I fear it. I do not expect his atrocious evil, or his form of Nazism, or his kind of Wehrmacht, to spring, from the soil of Germany, or from anywhere else. But there is today a hunger in the West. Our gray democracies have, materially, delivered what they promised. There is peace, generally speaking, there is prosperity. But where are the anthems? Where are the bugles? Where are the banners? Where is -- oh, where -- the struggle? A feeling of pointlessness pervades all the West, and here and there, and now and then, one hears the ominous cry in response to this futility: How can we be made strong, without the struggle, how are we to be purified? Do we not need a leader, a new Nietzschean man of will?

We may think that the old urges have been harmlessly channeled into ego trips, into the disco and titillations of one kind or another, into the pursuit of the crafts and the pastoral life. But we should remember the scene in the film version of "Cabaret," when it takes only a boy in shorts to turn a pastoral lieder, within no more than a stanza or two, into the marching beat of "Tomorrow Belongs to Me."

We should always pay attention, especially in the young, to the few who are sleepless: the active, the articulate, the organizing, the dedicated, the relentless, the unsurrendering, the violent, the waiting. They may seem only to be a few cells, but cells multiply into coral reefs. They often speak with a terrible accuracy for resentments much wider than those which they appear to represent. When the time is ripe, they are the rescuers from futility, the summoners to struggle, the saviors and -- ah! -- the purifiers.

Otto Strasser was an early follower of Hitler who later broke with him, and he once described the Hitler whom he followed in the climb to power in words that are troubling, because one never knows when the same appeal may not attract:

"Hitler responds to the vibrations of the human heart with the delicacy of a seismograph . . . [He possesses] an uncanny intuition, which infallibly diagnoses the ills from which his audience is suffering . . . [He] enters a hall. He sniffs the air. For a moment he gropes, feels his way, senses the atmosphere. Suddenly he bursts forth. His words go like an arrow to the target; he touches each private would in the raw, liberating the mass unconsciousness, expressing its innermost aspirations, telling it what it most wants to hear."

There are far deeper and more general resentments in our western societies today than we are willing to recognize. Our democracies are in danger of breeding a population not of slaves, indeed, but of helots who are condemned to lives of futility and no responsibility. Somewhere the new man of will may already be sniffing the air.