We came across their camp hidden deep in the pine forests that cover swathes of the Turkey-Syria frontier. It was the month of March and patches of snow from a heavy winter still lay on the surrounding windswept hillsides.

As he spoke, his agitated eyes peering out from holes in the black balaclava ski mask he wore, told of the traumatic experience of the previous few days in the village of Ain al-Baida just inside the Syria side of the border in Idlib Province.

“The tanks came first and started shelling,” the young man, a fighter with the rebel Free Syrian Army (FSA), told me. He himself had been a former soldier within the ranks of Syrian president Bashar al-Assad’s government forces, before he defected to the opposition rebel side, and for that reason wanted only to be identified by his first name, Khalil.

“Assad’s soldiers fought like crazy men, we tried to hold them back but we have no real weapons, only some Kalashnikov’s and pump action shot guns,” Khalil explained describing the battle that day back in 2012 at Ain al-Baida.

As we talked I couldn’t help noticing that his boots and camouflage trousers were still caked in mud from the hasty retreat he and his fellow fighters had made through the woods and across the hills from the village.

At the end of this one small action, Khalil and his comrades had been routed in what would be the first of many though later much bigger battles between government and opposition forces for control of Syria’s Idlib Province.

In the intervening years since 2012, territory and strategic positions have been taken and retaken by both sides in this war of attrition in the country’s northwest.

Now though the denouement of that protracted struggle is about to be enacted in a showdown some believe could be the last major offensive in Syria’s civil war.

It’s a battle President Assad in Damascus hope swill deliver the final military blow against the rebel fighters who, like the young man Khalid I met back then seven years ago, rose up and resisted demanding regime change in the country.

Today backed by his Russian and Iranian allies Mr Assad is determined, whatever the human cost to retake Idlib.

And like other Syrian cities that have borne the brunt of such onslaughts against them by myriad forces in this multinational proxy war, that cost could be high indeed.

It was just a few days ago that Staffan de Mistura, the United Nations special envoy to Syria described what is unfolding as a “perfect storm coming up in front of our eyes”. In the meantime Syria’s government has been busy mustering thousands of conscripts to bolster its depleted forces.

At sea Mr Assad’s allies in the shape of the Russian Navy is just offshore barely a few hundred miles from the likely frontlines with 26 warships including the missile cruiser Marshal Ustinov and 36 planes among them strategic bombers. It’s the biggest show of force since Russian President Vladimir Putin intervened in Syria in 2015.

The firepower the Russians could and most likely will deploy is terrifying, leaving the almost three million civilians in Idlib wondering what their fate will be.

For Syria and its Russian and Iranian allies this is the chance they have been waiting for to crush the opposition of some 30,000 rebel fighters that include Syria’s strongest rebel faction, Hayat Tahrir al-Sham, or HTS, which is affiliated with al-Qaeda.

But there are other powerful rebel forces in Idlib too, including the Turkish-backed National Liberation Front (NLF) that also includes big hardline Islamist groups as well as others fighting under the banner of the Free Syrian Army.

Should all out fighting between these groups and Syrian government forces ensue in the coming days, then there are a number of crucial factors worth watching out for.

To begin with there are fears that illegal chemical weapons might again be used to terrorise the local population into submission.

Documented evidence already exists of numerous previous instances when such weapons have been used in Syria by the Assad regime, while claiming it was staged by rebel forces. Equally it is not outside the realm of possibility that jihadists might indeed launch their own black flag operations using chemical weapons to force wider international intervention against the regime in Damascus.

But this unpalatable threat aside and as evidence elsewhere in Syria has shown, conventional weapons themselves, including airstrikes and bombardment be they Russian launched in places like Aleppo or US launched in Raqqa, have accounted for that vast majority of civilian casualties and widespread destruction of infrastructure.

For precisely this reasons it’s by far the humanitarian crisis that might occur in Idlib that is causing the gravest concern.

According to the US-based Soufan group, an independent security and strategic analysis company, an attack on Idlib would represent a “singular catastrophe in a catastrophic war”.

In a conflict in which more than 350,000 people have been killed, and 11 million have already fled their homes, what might befall Idlib would add substantially to that appalling loss.

Already a staggering 1.5 million people in Idlib have been displaced by earlier waves of fighting in Syria, many of them bussed there under temporary ceasefire deals, with around 275,000 of them living in poor conditions in tented settlements that often lack basic sanitary conditions. Throughout the province some 1.7 million are already also relying on food aid.

It doesn’t take a humanitarian expert to work out that any major military offensive will make an already dire situation into something rarely seen in Syria even by the civil war’s own terrible standards.

Over the past days the ominous signs of what might follow have already begun as the Syrian army and Russian aircraft began shelling and bombing rebel positions.

The lives of “millions of people in Idlib are now in the hands of Russia, Turkey and Iran,” said human rights group Amnesty International in a statement yesterday, referring to a summit to discuss the crisis scheduled for Friday in the Iranian capital Tehran.

No one though is holding his or her breath over a positive outcome. Hard as it is to imagine, yet another swathe of Syria looks set to become a charnel house, as the world looks on powerless to prevent it.