Their faces said it all, a tableau of fear, confusion and exhaustion.

One little boy clutched his mother’s hand, while his sister cowered close to her side, wary of the strangers around her.

Though no more than seven or eight years old, there was something about the look on the little girl’s face that made her appear older than she was.

It was a telling look, a strange mixture of profound sadness, apprehension and resignation that spoke volumes about the traumatic experience she and her siblings had undergone.

In their flimsy plastic sandals they had walked for up to eight hours across the desert scrub in oven-like temperatures that hovered around 54 degrees Celsius.

On the horizon behind them the dense black smoke billowing up from around the oil town of Qayyara told of the fighting between the Iraqi Army and Islamic State (IS) fighters that had forced them to flee their homes.

They had come here to the outskirts of the Kurdish town of Makhmour south-east of Iraq’s second largest city Mosul, with only what they could carry. Lives distilled into a few bulging holdalls and carrier bags and their future uncertain.

“It’s like being in prison, you cannot move, it’s like a psychological war the way Daesh control everything,” one man who preferred not to be named for fear of reprisals, told me using the commonly used Arabic acronym for IS that has become infamous here in Iraq and across the world.

He told too of how he had been studying languages in the hope of becoming a translator but that for two years under IS control that ambition has become impossible to realise.

“There are no schools, everything is forbidden only looting and weapons flourish,” he continued.

As we talked, behind us sitting in the shade of a ramshackle tarpaulin tent strewn with litter and other filth sat the man’s wife and two-year-old daughter, whose name he told me was Farha.

In Arabic Farha, means “happy occasion” or "joyous time” but there was only worry for this family as to what lay ahead for their daughter.

“We came without Farha’s birth certificate or ID and this could cause us problems, for getting registered and moving to Dibaga camp,” the man fretted, as his wife with their tiny daughter in her lap, sat with the few biscuits and water they had been given on arrival at this crossing point.

Dibaga camp for internally displaced people (IDP) sits on a baking windswept dun-coloured desert plain not far from Makhmour.

Built originally to house 3,500 people, the camp is now bursting at the seams, with the initial allocated area already housing more than 5,000 people.

Twelve thousand more are being moved into extensions to the camp nearby, including the local sports stadium, but the authorities cannot keep pace with the needs of the thousands who now arrive daily.

“Right now we are short of some 1300 tents," says Rzgar Abed, Dibaga camp manager, who works for the Kurdish humanitarian group, Barzani Charity Foundation (BCF).

“See for yourself the conditions people are living in, and this is only the start,” insists Abed, before assigning one of his workers to take me around the camp.

In Dibaga’s narrow confines running from outside his office, there is the fetid stench of human waste. Some 30-40,000 people are now estimated to be sheltering in Dibaga’s patchwork labyrinth of tents, prefab containers, makeshift shelters and municipal buildings, or just sleeping out in the open on crushed down cardboard boxes.

These numbers are nothing compared to what is expected in the months ahead as the battle for Mosul intensifies reaching the city’s heart and forcibly spewing out more of the million and a half residents still holed up under the barbaric rule of IS cadres in the city.

This wave of humanity will only add to the already enormous humanitarian crisis Iraq now faces.

In the country’s western Anbar province, where Iraqi forces cleared cities and towns of IS earlier this year, more than a million people there remain displaced, most of them unable to return home.

Overall in Iraq, some 3.3 million people have been forced from their homes since IS first began growing in strength in early 2014.

Last month at an international conference in Washington more than a dozen nations pledged some $590 million in aid money for Iraq. But the UN says it still has less than half of the funds needed to prepare for the full impact of the humanitarian fallout from the Mosul military operation.

Meanwhile the situation on the ground for ordinary Iraqi civilians caught in the crossfire is rapidly deteriorating.

Walking through Dibaga camp that afternoon, the unrelenting sun beating down on its dust covered tents I encountered some crowds of angry young men, gathering around administrative offices demanding proper shelter or permission to leave the camp entirely. For many here the conditions have simply become unbearable.

In another section my BCF guide took me to a building in which newly arrived women and children were crammed together waiting for full registration and the hot food provided for them.

“Most are here for five or six hours, before we move them to the camp proper, but right now there is such a shortage of space we have a long delay,” says Hozr Mohammed, of BCF.

Nearby too in another section separated from the rest of the camp, families call through chain link fences in search of loved ones partitioned by a lengthy interrogation process.

This process, explains Hozr Mohammed, is a vital part of the security clearance that must be undertaken to try and root out IS members who have escaped or are attempting to infiltrate areas controlled by the Kurdistan Regional Government (KRG) by coming through posing as displaced civilians.

“The authorities have security checks here based on previous information from computer data bases in the Mosul region, but it can be like searching for a needle in a haystack given that many of these IS fighters are not even from the area or country,” he tells me.

In the months ahead, as IS are pushed from Mosul along with hundreds of thousand of civilians, one can only guess at the scale of the security problem the KRG will face. Almost inevitably some IS fighters will slip through the net.

Major General Sirwan Barzani, nephew of the current Kurdish president and commander of the frontlines around Makhmour and the neighbouring town of Gwer, echoed these security concerns.

“Security-wise it’s very hard for us,” General Barzani confessed, as we talked at his military base dubbed Black Tiger, between the Makhmour and Gwer frontlines.

“If we don’t accept these IDP’s Daesh will kill them, and if we do accept them then Daesh might be among them, so in the end we accept them and take this risk for humanitarian reasons.”

Back in Dibaga camp many of the displaced now living there are able to give first hand accounts of the way IS fighters ruling them struggled to keep control as the Iraqi Army closed on villages strung along the bends in the Tigris River near the town of Qayyara.

As the Iraqi Army drew near, IS became even more brutal, killing deserters and relying on younger and younger recruits, according to residents who fled battleground territories. At one point, almost all the militants guarding the streets were teenagers some say.

“They started making raids on houses, arresting people and beheading them,” says Jarjis Muhammad Hajaj, who was among thousands of residents who fled fighting before ending up in Dibaga Camp.

Around the oil town of Qayyara where I watched coalition airstrikes pound IS positions before the Iraqi Army’s all out assault, IS fighters questioned and sometimes demanded fees, from anyone trying to cross the Tigris to markets in the town.

Under pressure militarily the jihadists have increasingly shown signs of panic and paranoia. IS’s fear of informants it’s said has fuelled a crackdown in Mosul itself.

Just a few weeks ago, the group released a video titled “deterring the traitors,” where six young men are shown being killed on a city street.

In the video, the narration accused the men of being “the eyes of America,” suggesting they were spies.

As the fight for Mosul builds, horrors of this kind are certain to increase as will the ebb and flow of civilians displaced

On the outskirts of Qayyara at one key Iraqi army checkpoint, I watched as truckloads of displaced people some fleeing, others returning to villages already liberated from IS, came and went across areas still littered with IS mines and booby traps.

Just who exactly controlled some villages was often not clear - and sometimes it was not the Iraqi Army who currently lead the advance in this sector of the Mosul campaign.

In one village near to the Tigris and close to Qayyara, I arrived to find it under the control of nervous armed tribal militias and displaced civilians sheltering in an abandoned school.

Heaps of raw garbage lay in the street outside the schoolyard, next to a waterpipe that was the only source of drinking water in the area for hundreds of people.

Inside the schoolyard flanked by desks and blackboards mainly men and boys congregated some carrying Kalashnikov assault rifles.

“So far it’s too dangerous to return to our villages though they are very close, just a few kilometres away, but some Daesh are still around,” one man told me giving only his first name as Abdul Halim.

In the chaos of the push to retake Mosul from IS, scenes like this will doubtless be repeated across Iraq’s Nineveh province, one of the most complex in the country in terms of ethnic, sectarian and tribal makeup.

This very diversity has given rise to real fears of what might happen in the wake of Mosul’s liberation from IS.

While victory against the jihadists in the city is possible, a grave danger to the wider security of Iraq some say is staring the country in the face.

The problem is, once IS is defeated, there is no guarantee those people displaced will be able to go home or that a political solution for running Mosul and the wider province will be in place to allow peace and stability to prevail.

Time and again during my time in the region officials from both the Iraqi Army and Kurdish Peshmerga warned of the dangers that might arise from a failure to have a political blueprint ready to rule Mosul once the military campaign is over.

For the moment though that process is unfortunately very much on the backburner as priority is given to the battlefield ousting of IS from the capital of their self-proclaimed caliphate.

That the battle for Mosul will be colossal and bloody is certain. That the humanitarian crisis accompanying it will be equally huge and dire in terms of human suffering is also certain.

Speaking recently, Falah Mustafa Bakir, the foreign minister of the Kurdistan Regional Government, stressed that the region is already “stretched beyond our limits” when it comes to coping with the numbers of those displaced by the war in Iraq and neighbouring Syria.

The Kurdistan region he says will be the “ground zero” for the humanitarian catastrophe that is approaching over the battle for Mosul.

In the past few weeks while touring the frontlines of this battle, I have met some of its combatants and civilian victims.

Listening to their stories what is certain is that many more are set to die or find themselves fleeing the gathering storm looming over Iraq’s second largest city.

Tragically, what I witnessed is little more than a bitter taste of what is likely to come.