It’s the signs of life; the glimmers of hope and resilience. Two babies, found alive in a cupboard where their parents hid them ­before being slaughtered.

A woman’s first gasps of fresh air after 10 hours huddled in a bomb shelter with six children. And the old man, standing in front of his burning home in a street full of corpses, who told the young men and women in uniform “Yihiyeh tov” – everything will be all right.

Those words crushed Major G, a battle-hardened operative with Unit 669 who gave The Australian a harrowing first-hand account of October 7.

His story is stomach-turning in parts, but it bluntly answers the question of why Israel has mounted a powerful ground incursion against Hamas in the Gaza Strip.

“We’re not acting against an army,” Major G said. “This is evil, unequal to anything I can think about.”

Major G’s identity is suppressed because he’s attached to a storied special forces outfit ­renowned for its daring and ­spectacular aerial rescue missions. Every year about 1000 soldiers apply to join Unit 669 but only 30 are accepted after a brutal ­selection phase and 22-month training course.

If 669 operatives are suiting up in a Black Hawk, it means all other options have failed – it could be a pilot downed behind enemy lines, a civilian trapped in 3m waves, or a wounded soldier needing extraction from the hellfire of northern Gaza. In the five weeks since the start of the war, at least 150 of these operations have been carried out.

Major G is 29 and has the millennial gift for discussing his experiences. For 40 minutes he retells the events of October 7 in as much detail as possible, starting with the phone call that woke him on that fateful Saturday with instructions to get to a military base.

With two 669 operatives he drives south in a pick-up truck, ­receiving mission objectives to rendezvous with more soldiers and head into Nahal Oz, a kibbutz overrun by terrorists on the border with Gaza.

But the truck hits a traffic jam, the highway crowded with police cars and paramedics. It’s here that Major G catches his first glimpses of the dead and injured, the scale of what’s unfolding.

There are bodies slumped between trees, laid out on the side of the road. They’re lying prone in a dusty field, everyone dressed as though they’re at some kind of party. He doesn’t know it yet, but Major G is standing on the outskirts of an electronic dance music festival where 270 civilians were gunned down with Kalashnikovs as they fled for their lives.

“For the first time we actually faced the horror of what’s happening,” he says. “People are screaming, bleeding to death on the floor there, and I start treating them, you know, with this instinct that I’m a paramedic. At some point the soldier with me, he stops me and says, ‘We have to continue, we have to get to where our mission is.’”

Once inside Nahal Oz a teammate asks the driver to stop their armoured vehicle. He sees a dog barking next to a bin, calling Major G to come examine its contents, a dreadful sight that can never be unseen. “There was a baby inside stabbed multiple times, maybe a year old,” he says. “It’s not something you can imagine would ever happen to you, finding a stabbed baby in a trash can.”

Moving house by house with special forces, frequently under fire, he locates a woman in a safe room, coaxing her out by speaking in Hebrew to assure he’s not a ­terrorist. Ten hours of sitting in the dark with six children has left her exhausted, and she’s incessant about the stern words she’ll be having with her husband when she finds him. We can’t live like this. This isn’t a life. We’re sleeping for a week at a time in a bomb shelter. This is the last straw.

Major G nods patiently as he examines each child to make sure they’re in good shape, then apologises for interrupting. He needs a sheet, he says, a long one, something to clean his gun very thoroughly, he tells her, but instead he’ll use it to cover the body of a man he encountered on the way inside, lying on the porch. In the chaos, he failed to make the connection. “He (the husband) ran out in the morning, I guess, and tried to protect his family.”

These aren’t even the worst scenes he’ll discover, not by a long shot. Nahal Oz is in bad shape but at the village of Kfar Aza the injuries are so extensive that Major G starts making snap decisions about whose life he can save. A man with a pulse is brought out to him, covered in gunshot wounds. “I just don’t have the means to start treating him,” he says. “There are so many other people who (need) my hands, my equipment.”

A car pulls up and a soldier emerges with two babies. “They looked really young, maybe a year old, and I checked them to see if they’re injured. I understood the parents were slaughtered at the entrance of one of the rooms of their own home, and they managed to hide the two babies inside a closet.”

Social media is a cesspool of cavilling over the infant victims of the Hamas atrocities, but also the violence inflicted on civilians. To even engage in this grotesquerie requires a wilful snubbing of the evidence – from bodycam footage to instructions the terrorists were carrying to the candid, pathetic ­admissions they made to authorities after their capture. It’s for this reason that the Israeli Defence Forces encourages soldiers like Major G to tell their story.

In an era of misinformation, of Holocaust denial, the government has been forced to stoop to obscene lengths to convince the world that what happened, happened. Around the world it has held private screenings of a 43-minute video depicting murder of the coldest degree, some of the clips uploaded by Hamas itself, just to assure foreign journalists, intelligence officials, politicians and diplomats that the published accounts of first responders haven’t been fabricated.

It’s approaching 5am when Major G rolls into Kibbutz Be’eri, the last of the three he would be asked to attend, and where terrorists are holed up in houses with captured civilians as human shields, preventing the IDF from storming the properties. Somehow, the scenes here are the worst he’s encountered. “If hell would have been drawn by someone, that’s how it would look,” he says.

Scanning for survivors inside a house, he opens a door expecting to be met by a terrorist. Instead he sees two girls, about 13 or 14, one lying on the bed, deceased, with black marks on her legs. The other is on the floor, blood pooling around her head.

“She was shot in the neck and her pants were pulled down,” he says, observing semen on the lower part of her back. “She was brutally raped and then executed, or executed and then raped – I don’t know what’s worse.”

The catalogue of wretchedness is endless, but some were rescued. Residents of Be’eri, old enough to have lived in the shadow of the Shoah, sit in the gutters at a staging point near the entrance to the ­kibbutz, their homes aflame, ­family members dead.

“Everything around them is just bodies,” he says. “Many of them are people they knew, just sitting near the bodies of their neighbours, their children and grandchildren.”

And it’s here, amid the depths of this misery, the pent-up grief, that it takes just two words, spoken by an 80-year-old man, to pierce the layers, the armour, that’s been fortifying this battered young soldier’s heart since his phone rang at 8am the previous morning. More than a month later, the words still pinch. Yihiyeh tov. It will be okay. “That kind of grabbed me in the guts in a way I can’t explain.”