Not exactly a call to arms perhaps, but it was a call for muscular arms, strong backs and sturdy legs, along with energy, commitment and a readiness to rough it. On 11 August 1963, under the headline "New siege of Herod's fort", the Observer published an appeal for international volunteers to join the excavation of Masada, an ancient fortress in the Judean desert. Interested parties had to be available for a minimum of two weeks, fund their own travel to and from Israel, be prepared for harsh conditions, and apply in writing to PO Box 7041, Jerusalem.

"One of the greatest surprises – and delights – of the enterprise, long before we had put scoop to rubble, was the response," wrote Yigael Yadin, the former Israeli military chief of staff turned archaeologist, who was the mastermind, driving force and public face of the dig, in his 1966 book Masada. "We were flooded with applications."

According to Ronald Harker, an Observer journalist who introduced a book on Masada produced by the paper, the applicants were "men and women, rich and poor, young and old, and from 28 countries. None was under any illusion about the nature of the task ... It was made clear that the work would be hard and often boring, the food adequate but not appetising, that the heat of the day would be severe and the nights cold, the comforts (with 10 beds to a tent) would be limited, and recreation primitive if not minimal. Yet ... pleas to join from all parts of the world continued to flow in."

Almost 10,000 people responded to the appeal; many were turned away by overwhelmed organisers. By mid-October the first batch assembled at the desert town of Arad, to be taken by truck to the base of the majestic 2,000-year-old clifftop fortress that was waiting to be uncovered. "They arrived by bus, or hitch-hiked, with rucksacks, suitcases, banjos and typewriters, in shorts, jeans, slacks and skirts," according to a contemporary account in the Jerusalem Post. "Bearded and bespectacled, clean-shaven and clear-eyed, they came from all over Israel and all over the world.

It was the biggest archaeological dig in the world. Masada had become the magnificent fortified home of Herod the Great, built on cliffs overlooking the Dead Sea – an extraordinary feat of architecture, construction and engineering. It was also the setting of one of the most powerful moments – or myths – in Jewish history. According to the account of the Jewish-Roman historian Flavius Josephus, 960 Jewish rebels committed suicide at Masada rather than be captured by the Romans following a siege. The story of heroic resistance, and the choice of death over enslavement, became a powerful symbol in the nascent state of Israel.

Masada is the site of an ancient fortress based in the south of Israel. Photograph: Observer

The site had been discovered 125 years earlier, but it was not until the 1950s that two archaeological surveys led to the decision to launch the excavation and Yadin was persuaded to lead it. At the time, Masada was isolated at the southern end of the Dead Sea with no paved roads near the site. A major dig would require not just the leadership Yadin could provide, but also his logistical expertise and leverage with the army in creating a camp and keeping it supplied.

"Only Yadin could arrange such a project," said Guy Stiebel, doctor of archaeology at Jerusalem's Hebrew University and a Masada expert. "People regard archaeologists as Indiana Jones figures, but managing an excavation such as Masada is like a jigsaw puzzle. You're out in the desert, you have to make sure there's enough water and food for a camp of 300 excavators. It's not just a scientific achievement, but an administrative and logistical achievement."

Some of the volunteers had a brutal induction into camp life. "We were trucked to the foot of the snake path on the eastern side of the mountain," recalled David Stacey, now 70, in a memoir. "Yadin's idea was that the best way to introduce the volunteers to the rugged grandeur and isolation of the site was for us to have to climb the mountain and drop down to the campsite below its western scarp."

But the group's arrival coincided with torrential winter rains. "We were soaked. The trucks had not been able to negotiate the swamped desert track from Arad, so our luggage had not arrived and we were without a change of clothing ... The continued rain had turned the campsite into a running stream. I remember sitting, cold and wet, on a no longer dry bed, watching as the weight of the tent slowly dragged the pegs through the sodden ground towards me until the tent finally collapsed. Welcome to Masada."

It was a tough start to a harsh existence: up at 5am, eight hours of hard slog on the site, a diet mainly of bread, margarine, boiled eggs and processed cheese, army tents crowded with volunteers. "But we were young, and it was perfectly acceptable," Stacey told the Observer. "And the work grabbed our attention, it made the spartan conditions acceptable. It was physically very hard – an enormous amount of heavy rock lifting."

The attraction of the dig, said Stiebel, was not just the "joy, mystery and riddle of archaeology", but also the geographical setting and political context. "Israel was conceived differently than it is now. The kibbutz ethos was tremendously attractive, and Israel – a newly created country — was considered an underdog surrounded by enemies. Plus there was the charm of the east, sun, desert, isolation, the Dead Sea: the most beautiful scenery in the world." By the time darkness fell, the evenings stretched ahead with little to do except clean shards of pottery and listen to the occasional lecture on archaeology. The volunteers created their own entertainment with music, singing, dancing — and illicit activities.

Among them was an Irish musician named Joe Dolan. "He and his guitar soon became the centre of many an evening's entertainment, to which I could add an occasional English folk song," wrote Stacey. "Joe determinedly drank to excess. If the party was away from our tent, it was essential at the start of the evening to ensure that a barrow was on hand in which he could be unceremoniously wheeled home at the end of the night. Occasionally he remained in the barrow till the loudspeakers woke the camp with the call Boker Tov [Good morning]."

Dolan composed a song about his travels entitled Trip to Jerusalem: "I came from Dublin to Jerusalem town/Had a drink or two on the way down... Down to the desert then I went/Diggin' up history, livin' in a tent." It was later recorded by Christy Moore. Another evening pastime involved treacherous journeys in the dark for romantic liaisons. "There were no 'married' quarters, so assignations ... usually took place 'up the wadi' [riverbed] where snakes and scorpions proliferated. Late returners to the tent would be asked how successful their 'wadying' had been, and there was no point in claiming you'd been out to admire the desert stars, no matter how truly magnificent they were!" wrote Stacey.

Archives from the dig later revealed that the camp authorities believed Stacey to be a "wild guy and bad influence on the impressionable Israeli youth". But he was also acknowledged to be a good worker so – unlike a handful of fellow volunteers – he was not thrown out.

By the end of his allocated fortnight, Stacey was hooked. He stayed for around three months, but by the end "the magic had gone", he said. "The halutz [pioneer] spirit was no longer dominant; it was like working on a building site." But he went on to study archaeology and work on other excavations. Much of the credit for Stacey's and other volunteers' lifelong interest in archaeology was due to Yadin, who died in 1984. "He was an inspiration, charismatic, very good at informally explaining to people what they were doing and what we could expect to find," said Stacey. "He remembered all our names – and there were a lot of us – and showed us respect." But he seemed detached, with no sense of humour. "He took himself extraordinarily seriously."

Yadin had recruited David Astor, the Observer's editor, to the Masada cause, and the paper carried exclusive dispatches from the dig, some by "a special correspondent" believed to be Yadin himself. "There was careful news management," said Stiebel. "It created a stir, and rightly so."

In 1966, the Observer co-sponsored a three-week exhibition on the dig at the Royal Festival Hall in London, and published an accompanying commemorative book, telling the story of the rock fortress and its excavation.

Masada is now the biggest tourist attraction in Israel outside Jerusalem, drawing 800,000 visitors each year to view the fortress's remains and its stunning vistas. "It's a very powerful place," said Stiebel. "To this very day we are discovering new elements: there are still riddles to be solved. The nature of our science is such that, when we discover something new, it's not only that you find an answer, it leads you to the next question. I've been at Masada since 1995, and I still have light in my eyes when I speak about it."

Eretz magazine is attempting to contact those who took part in the Masada excavations of 1963 and 1964. If you took part, please contact Yadin Roman at Eretz magazine: masada.eretz@gmail.com