Sir Martin Gilbert doesn't rant. He doesn't pound the table to hammer home this or that perceived parallel between the rise of the Nazis and that of Iran's fundamentalist regime. He doesn't raise his voice to suggest frustration at this or that failure to learn the lessons of history. He doesn't even stridently insist that Iran's agenda, and its march toward a nuclear capability, constitute a grave and serious threat. What Gilbert, the official biographer of Winston Churchill and prolific World War II historian, does do, in soft, almost diffident, but thoroughly articulate tones, is emphasize that the mistakes of 70 years ago cost the free world a terrible price. He explains how those mistakes came to be made. And in so doing, he provides a historian's context for today's challenges, a guide to today's perplexed leaders that we had all better fervently hope they follow. Speaking to The Jerusalem Post this week ahead of a lecture on Churchill that he's giving at Jerusalem's Moreshet Avraham synagogue on Sunday, the London-born Gilbert's first, and most important historical lesson about the Allied failure to thwart the Nazis until they were almost unstoppable is: Take your enemies seriously. Because when it came to the Nazis, people didn't. And by people, Gilbert means the Allied leaders who needed to have known better. "A grave mistake was made in the 1930s in finding all sorts of reasons for not regarding the Nazi threat as being a serious threat. Therefore, when you're working out your thoughts on the current situation, about fundamentalism, just remember that it is very easy for highly competent, educated, civilized, sophisticated people to find excuses and benign explanations for everything that happens," he says. Compounding that failure in the 1930s, as the Nazis' rapaciousness became ever-more stark and should have become ever-less possible to explain benignly, Gilbert goes on, was the refusal nonetheless - of German Jews, of the British government, of most of the watching world - to acknowledge what was unfolding before their very eyes, and thus confront it effectively. "The main argument towards the [Nazi] threat was: 'It must modify; these are extremes which surely will modify.' Of course, many German Jews took the same view as the British government on this... But when the dangers actually worsened, the people who had argued 'it will surely modify,' didn't say, 'Wait a minute. My premise is now destroyed.' Instead, they said, 'This can't really be that grave a threat. This can't be truly an evil force,' and, 'Well, it's not really what it seems." The "German Jews" reference strikes personally home. At once very Orthodox Jews and very German, my own family wanted for a long time to believe that their fellow Germans would come to reject Adolf Hitler, that Nazism wouldn't last, before the daily evidence - including the suicide of one of my lawyer grandfather's Jewish clients, an innocent man unjustly jailed - belatedly persuaded them that there was no longer justice for Jews in the fatherland. And listening to Gilbert, my mind flashes from the Horovitzes in 1930s Frankfurt to the present, to the unmistakable evidence of Iran's genocidal aspirations for Israel - its delegitimization of our state, its public incitement against us, its manufacture and display of missiles geared towards us, and that relentless nuclear program - and to what often seems like willful international determination to say precisely what Gilbert recalls the apologists saying of the Nazis: This can't really be that grave a threat. Gilbert offers specifics from the 1930s, examples when honest internalization of what Hitler was up to should have necessitated the robust response that would have thwarted him at so reduced a price: First, the remilitarization of the Rhineland in 1936, hailed risibly in a Times of London headline as "A Chance to Rebuild." Next, the annexation of Austria, "which was seen somehow as the natural evolution" even though Austria and Germany had never been one country. Then, Hitler's assertion at Munich in 1938 that he didn't want to rule Czechs even as he was seizing the Sudetenland region of Czechoslovakia, "which was disastrous for the survival of Czechoslovakia and the security, basically, of the West. He was taking this great industrial zone, these great industrial resources, and [destroying] Czechoslovakia's defenses." But again, "people rationalized. They didn't acknowledge how far things had moved from 'A Chance to Rebuild.' Hitler was taking the territory of another country, and still was producing a reason for so doing which was accepted as plausible." The ostensibly "alarmist" Churchill (who was to take over as prime minister in May 1940) had been warning all through this period that by the time the apologists woke up and belatedly recognized the need to "take a stand," the means to mount an effective fightback would be much reduced. And so it proved: When the bitter truth of Nazi ambition could no longer be apologized away, with the invasion of Poland in 1939, says Gilbert, "you'd lost your allies, you'd lost territory, you'd lost raw materials. You were in the weakest possible position." GILBERT DOES not underestimate the challenges that face leaders down the ages in assessing the potency of a threat, and the weight of responsibility in choosing to ignore, contain or confront it. Indeed, he faults Churchill with a reluctance to tolerate loss of life in the 1944 Normandy landings - a misjudgement that, had the British prime minister not been overruled by President Roosevelt, would have had "desperate consequences." In the two months ahead of the landings, Gilbert notes, in order to avoid being driven straight back into the sea, the Allies had to destroy all the German railway junctions, munition dumps and airfields within a 200-300 mile radius of both Normandy and, because of the elaborate deception of the Nazis, within a similar radius of Calais as well. The projected loss of French and Belgian soldiers' lives was in the order of 20,000-40,000 "and Churchill didn't want to go ahead" with the bombings. But Roosevelt insisted his troops be in "the minimum of danger" when they landed and so the preparatory attacks proceeded, with what turned out to be 7,000-8,000 French and Belgian fatalities. Thus leaders have to grapple with questions of human cost when confronting threats, questions of "how many people you can ask your society to lose. You have to make a calculation..." And that dilemma carries the risk of leaving it too late - as is feared with Iran today, and as certainly happened with the Nazis. The Nazis' eventual defeat, indeed, was feasible only after Hitler's "foolish mistake" of declaring war on America. "There were four days in world history" - December 8 to 11, 1941 - "when the United States was at war with Japan and not with Germany and had no intention of going to war with Germany," Gilbert points out. Four days when "the situation for the Western World and Britain was desperate. They were certainly the four worst days in Churchill's life." But the root failure, he stresses, "was that when Britain and France went to war in September 1939, they had already so neglected their defenses as a result of appeasement" that what unfolded was "a six-year war rather than a six-month war." Look at the German records, he says. Hitler's generals were saying in 1938 that if Britain and France declared war, "there's nothing we can do. We can't win. We don't have the resources." In this light, the historian observes with dry understatement - implying but not verbalizing a parallel dismal procrastination in the face of evil - it would be "interesting" to hear the internal Iranian discussions today. "Essentially," he goes on, "appeasement gave the Germans time to create a war machine which was virtually impregnable," and which could not be overthrown or even seriously weakened for the first three years. Which facilitated the Holocaust? "Which facilitated all the evils that came with the German Nazis." To give just one example, Gilbert asks: Would 55,000 members of [the Royal Air Force's] Bomber Command have been killed if we [Britain] had prepared our air force properly in 1936, 37, 38, 39, instead of pursuing this extraordinary belief that you could do a deal with Germany; that you could even have some sort of disarmament; that it was 'only fair' to allow Germany to build up to your level because they had been 'so cruelly and wrongly disarmed at Versailles'? All this loose thinking arose from the basic premise that Germany wasn't a threat." THE "OTHER part of this equation," Gilbert says, is the question of allies. Britain's two late-1930s prime ministers, Stanley Baldwin and Neville Chamberlain, were firmly set against bringing in the Soviet Union as an ally. Churchill, second to none in his opposition to Communism, argued nevertheless that the Nazis were effectively the only enemy, and that alliances needed to be constructed with everybody who was threatened. Under parliamentary pressure, Chamberlain did send a mission to Moscow, but with instructions to stall. Yet had British policy been to create an alliance of threatened states, Gilbert stresses, "Poland could not have been conquered. Hitler was only able to conquer Poland via the Nazi-Soviet pact by basically partitioning the country. And the Holocaust, of course, was a Holocaust of Polish Jewry..." Now Gilbert allows himself to foray into the present. "When you are looking today at the role of the United Nations, of NATO, of the various forces that can combine [to deal with Iran], the Soviet analogy may be quite good here: if you can't get Russia on line, China, then you're already in a terribly weak position. Then you're in the same position as Britain and France were..." And so, regarding the Iranian nuclear threat, "it is absolutely essential that you tackle it with everybody who is in danger. And presumably everybody is in danger. Staying with Iran, Gilbert's concern is precisely over the gulfs between key players that are preventing more effective concerted action. "What alarms me is that Russia and China are moving forward to new 'great power' status. They see the world very differently. They see the rivalry with the United States, the European Union, Western values, as [offering] a way to get their client states back - you know, the old days when the Soviet Union had its client states in Africa, its client states in the Middle East. Still, Gilbert says he derives comfort from the fact that the Iranian threat is high on the global agenda. He's impressed that Israel has been "taking a lead on this," and says Israel is "gaining credibility" as a consequence, as European states increasingly internalize that they have deep domestic problems with Islamic fundamentalism. As a believer that much of history "comes down to the personalities of the leaders," furthermore, he's optimistic, where Iran is concerned, "that the leaders are capable of doing the right thing." But in a week when the French Foreign Minister Bernard Kouchner airily told me, basing himself on the (misleading) American National Intelligence Estimate of Iran's nuclear weapons progress, that "for the time being, we are not in a hurry," I have to ask Gilbert whether he thinks today's leaders truly understand the potency and urgency of the threat. "Do I have faith that the leaders know what the situation is?" he echoes. "Yes. If they don't, then we're in real trouble." Quite.