Perhaps the most extraordinary aspect of an incredible saga is the secrecy. The secrecy in which the machines were smuggled here in the first place. The secrecy that surrounded the construction of the factory and the recruiting of its work force. The secrecy that was maintained, truly defying belief, as production sped ahead - day after day, week after week, month after month and year after year - under the noses not only of the British but also of the workers' own unwitting companions. And even when it was all over, and the crucial mission had been astoundingly accomplished, the secrecy that was preserved for three more decades, long after secrecy was necessary anymore, simply because those who knew had been so utterly conditioned not to talk. So it is only now, in 2007, that the Ayalon Institute on Kibbutzim Hill outside Rehovot is marking the 20th anniversary of its restoration and inauguration - 20 years in which the public has been able to walk through this unique testament to pioneering fervor, innovation, bravery, resilience and dedication. And if Israel, at this remembrance-and-festivities time of year, of Holocaust Day and Memorial Day for Fallen Soldiers and Independence Day, needs role models as never before, exemplars of all that is best in our revival as a nation in this land and the human spirit that achieved and sustains that revival, then there are surely no more effective and inspiring such models than the few dozen people who spent their days in an underground factory built into a seemingly innocuous hill, producing the ammunition that was critical to the very establishment of this state. HOWEVER IMPROBABLY, it is in Poland just before World War II that this unlikely saga of Jewish salvation is rooted. The Hagana's weapons acquisitions man, Yehuda Arazi, got word in 1938 of a Warsaw warehouse filled with ammunition-making machinery that had fallen into disrepair. The machinery was purchased, crated and shipped off toward Eretz Yisrael - taking a last-minute detour via Beirut when it emerged that the British had been tipped off and were waiting to intercept it at Haifa. The machines were restored in 1945, when the Hagana recognized the imperative for home-based production of ammunition for the Sten submachine guns that were being manufactured by Ta'as, the nascent Israel Military Industries. And Kibbutzim Hill was selected for the site of the factory because it was at once isolated but not remote, because its elevation would facilitate the underground construction and, with that magnificent Yishuv hutzpa, because it was reckoned that the British would never dream of the Hagana hiding such a facility right under their noses alongside the Rehovot train station, continually humming with thousands of British soldiers. On guided tours today, they tell you that the whole facility was built in 22 days. It sounds unthinkable. Barely three weeks in which the ground was excavated, the foundations dug, the walls built, the ceiling emplaced and the hidden entrances prepared - the main one, under what would become the noise-absorbing laundry, and the emergency one, through which those Polish machines would soon be lowered, beneath the massive but movable oven of what would become a bakery. The workers were drawn from the Scout Movement's first settlement garin, youngsters from a range of backgrounds who included European immigrants, some of whom had come without their parents. One of the youngsters, Shlomo Hillel - later an aliya mastermind, politician, diplomat and much more besides - has recalled how, when the Hagana suggested they staff the factory, a "stormy" argument broke out within the group, who had dreamed of establishing "a seafaring kibbutz." But "national reason won out." Inevitably. The kibbutz would come later - Ma'agan Michael, established when the bullet-making was over, and still the home today of many of the Ayalon Institute's "graduates." The logistics of the bullet production, and the secrecy under which it continued from 1946 through to 1949, represent a triumph of trouble-shooting, smarts and guts over the odds. "It was hot down in the institute; people worked in light clothes and undershirts," Abraham Weinberg would write later. "The din was awful - hammers pounding, lathes turning... It was impossible to hear one another so conversations went from mouth to ear. People sang as they worked and each guessed what the other was singing and joined in. Even off-key singers were in demand since their tunelessness could not be heard. Morale was high and everyone who went down below viewed the work as sacred. People competed, not against someone else but to produce more than the day before." HOW TO keep their work secret from others working at the revived kibbutz, the so-called "giraffes" (one of whom almost gave the game away when she shrieked that she'd witnessed "people coming out of the ground" after entering the laundry through a door that had been left unlocked)? How to justify the drastic surge in electricity use (a "noodle factory" ran one explanation) and every other potentially suspicious aspect of their presence to the British? How to explain the import of the necessary raw materials (the metal casings were brought in as lipstick tubes) and how to smuggle out the finished bullets, up to 15,000 a day at the height of production, more than two million in all? How to maintain the health of the underground work force, not to mention the tans they ought to be developing through their purported agricultural activities in a distant field? How to keep them breathing, keep them safe, keep them sane? Solutions to each of these seemingly insurmountable dilemmas, and innumerable others, were somehow found. The factory survived discovery even when Lehi (the Stern Gang) blew up a British military train en route from Cairo to Lod on the adjacent railway tracks, killing 28 soldiers. Donning white coats, the kibbutz members flocked to the scene to offer medical assistance and, in so doing, averted a British search of their site. Even though test-firing of the bullets was carried out just a few paces away from the manufacturing machines in the very same underground facility, and even though the slightest miscalculation when handling the gunpowder packed into casing after casing after casing could have had catastrophic consequences, the factory thrived, disaster was averted, nobody was ever badly hurt. The man who snipped the casings to length - and who was known, of course, as the mohel - did lose part of a finger. But that was his own fault, he acknowledged when he revisited the site a few years ago. The way our guide told it, this unassuming elderly gentleman joined the tour like any other visitor, and only spoke out when the group passed by his machine. He injured himself, he said, because he was distracted by the loveliness of the lady operating one of the other machines nearby - later his wife. THE TALE of the Ayalon Institute remained almost the sole preserve of its heroic protagonists until the 1970s, when an Society for the Protection of Nature in Israel official, preparing a tour, came across mention of it in a neglected section of Ta'as chief Yosef Amidar's book En Route to the IDF. It became public knowledge after Shlomo Hillel wrote about it at around the same time, during his stint as Knesset speaker. On first reading the manuscript, his editor responded to the incredible saga by inquiring as to whether the author had forgotten himself and departed from factual recollection into fantasy. Hillel then began a campaign to have Kibbutzim Hill recognized as a national site, a goal fulfilled in 1986, a year before it was opened to the public. Another group of Israeli youngsters, from Labor's Noar Oved movement, lives there now, leading the tours and working with disadvantaged youngsters in the area. Hillel, 84, who today lives in Ra'anana, says that, like many of his colleagues, he did more dangerous things later (in a life that included heading clandestine immigration operations for the nascent state) but nothing more crucial to the existence of Israel. Once independence had been declared in May 1948, "weapons began to arrive from the Czechs and others," he recalls. But in the fighting over the previous six months, from the passage of UN Resolution 181 on partition until statehood, "the bullets made [at the Ayalon Institute] were truly critical. This was the Palmach's only supply in the fighting for Jerusalem, in Safed, all these critical stages before we even had a state, before the formal war against us was even declared. That ammunition was decisive in our ability to fight." Hillel, too, marvels at the maintenance of the secrecy, throughout the production years and over the decades beyond. "There must have been about 70 people actually working shifts in the factory," he estimates, "and maybe 200-250 in total who knew the secret, including the Ta'as people. We kept the truth from our friends, from our own families. Nobody leaked it." I have relied in this article on a short book by Eli Sa'adi which is sold at the site, but am conscious that I have not done the story of the Ayalon Institute anything like justice in a column. Maybe you'll want to see it for yourself - a restorative outing, particularly at this time of year.