Shattering the silence with a terrifying scream, shells pepper the fields ahead of us.

All around me, men grip their weapons tighter and scatter for their lives. Mail on Sunday photographer John McLellan and I dive to the ground as shrapnel screeches across the ruined landscape next to the River Tigris.

Fearing for my life, I duck behind a trench escarpment on the eastern riverbank. Here, crawling on my hands and knees and gasping for breath, I count the earth-shuddering explosions, each volley echoing in my ears.

Kurdish Peshmerga forces are tightening the noose on Islamic State in Iraq, pushing to within five miles north of Mosul.

Smoke rises following an ISIS attack near the Tigris River

We are the only Western journalists accompanying the elite Peshmerga – ‘those who have death in front of them’ – as they liberate village after village on the road to Mosul, Iraq’s second biggest city, which has been held by the murderous jihadis for nearly two years.

The rapid tempo of the Kurds’ recent victories – backed by RAF air strikes and SAS training teams – has led to speculation that IS could be driven out within months. Should they lose control, they will have nowhere else to go in Iraq.

The IS dream of establishing a caliphate would be gone for ever. But there is no sign yet that IS is prepared to stomach defeat, despite a drying up of fresh fighters and falling morale among its recruits.

Now, as the shells rain down on this ruined town of Qwer on the front line 20 miles south-east of the city, I am confronted by a terrifying sense of vulnerability.

Dust clogs my throat and sweat pours from my forehead. The temperature is 43C, but in the face of an IS artillery assault the heat doesn’t matter.

From the fires raging on the opposite riverbank and the plumes of black smoke rising behind the treeline, it appears high-explosive shells have landed a couple of hundred yards in front of us.

A minor adjustment to the angle of fire and they could have wiped us out. But a miss is as good as a mile to the battle-hardened soldiers slouching nonchalantly alongside me. These desert warriors, some in their 80s, have fought a remarkable rearguard action against IS. In late 2014, as they carved out their caliphate, they were less than five miles from Kurdistan’s capital city, Erbil.

Since then, with ancient weapons and sporadic support from the West, the Kurds have driven back IS by 50 miles, grinding down the jihadis and taking their own casualties from snipers, shell strikes, suicide bombings and chemical attacks.

We are accompanied on the front line by former British Army officer Hamish de Bretton-Gordon, who is training the Peshmerga in protecting themselves against gas and biological attack.

The offensive witnessed by The Mail on Sunday over the past fortnight – which has cost them six lives – has seen the Peshmerga recapture 12 villages that the Kurds claim as their own.

Invited by the Peshmerga to pose with an AKM assault rifle taken just hours earlier from a dead IS fighter, I reluctantly oblige in front of Qwer bridge.

I am distracted by the thought of how many lives it may have taken, but the Kurds hold up their camera phones and snap away. We then clamber into vehicles towards a Kurdish military camp another five miles behind the front line.

The Black Tigers, a division of the Peshmerga, comprise 40,000 troops between 18 and 83, some of whom have come out of retirement and are fighting without pay to save their nation.

They are spread out along a 600-mile front line across northern Iraq divided into ten sectors – six and seven, where we have been operating, are the most important because they are nearest to Mosul.

We are ushered into a brightly lit room and served sweet tea and pastries as we wait to meet the charismatic commander of Sector Six, Major General Sirwan Barzani, 46.

The offensive witnessed by The Mail on Sunday over the past fortnight – which has cost them six lives – has seen the Peshmerga recapture 12 villages. Stock image of an ISIS flag

‘Every day we give our blood on the front line and yet we have almost nothing to fight with. We need food, money, weapons, ammunition, night-vision goggles… We can’t even equip ourselves independently,’ he says.

‘The British have been very qualified with their military support for us. They gave us heavy machine-guns but little ammunition.

It makes me question what the motivations are in London. We are fighting IS for you. If it wasn’t for us, you would have to send your soldiers to fight instead. Why aren’t we getting more help?’

I ask when he thinks Mosul will be liberated and what role the Peshmerga will play. ‘The Iraqi Army is always saying it is going to happen but in my view it could be another 18 months and, whenever it happens, the Peshmerga will not be part of it. It is an Arab city. It is for the Iraqi Army.

But the morale of their soldiers is low and I don’t think they can remove IS from Mosul without us. But I repeat, we cannot be persuaded to join them.’

His words illustrate the labyrinthine complexities of the region. But there are serious implications for the coalition if the Peshmerga drop anchor once they have reclaimed their territories.