Bazwaya, Iraq (CNN) It is across the ghostly silence and dense dust of the berms between ISIS' Mosul and advancing Iraqi special forces that the final chapter of ISIS' extinction in Iraq will play out.

Yet at dusk on Saturday, the 2 kilometers between the US-trained Golden Division and the medieval world of the so-called caliphate suddenly were aflame with the loathing and terror of the world's war on ISIS.

Tracer rounds flashed across the horizon; the sparks and thud of countless explosions rocked the tiny village of Bazwaya, split in two by the closing stages of this battle. Ferocious and constant, it came closer and closer to the Iraqi base where we filmed from a rooftop.

By the end of the fearsome exchange -- which fell silent after heavy artillery flew over our heads -- a staggering 14 Iraqi soldiers were dead, some of the worst losses sustained by the unit.

Tip of the spear

When Maj. Hussien Hussien's Golden Division unit piled in to Bazwaya, they arrived as veterans of the war on ISIS. Having fought in Ramadi and Falluja, Hussien has a series of scars on his right ear from a rocket-propelled grenade attack months earlier.

They are the literal tip of the spear in the global war on the militant group. Despite the risk of being flanked, the men defiantly hold a tiny strip of land jutting perilously into ISIS territory.

The Golden Division moved into the town a few days earlier, putting them within 2 or 3 kilometers of the area near the Mosul city limits known as Gogjali. Hussien aggressively takes on ISIS positions, using tanks to pile into the dust at night and fire on areas from which his outposts are harassed. We watch as a series of rounds hit distant buildings marked by flags. In the darkness, we cannot tell if the flags are white to denote civilians, or black to denote those accused of using them as human shields: ISIS.

Hussien and his men use videos filmed from sniper scopes and Google maps to target their prey. The coalition has liaisons nearby, but not the volume of technology required to fully map out ISIS across this huge front.

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US-trained troops

The young Iraqis who make up much of this force have gone through American training and are buoyant when we join them. One, nicknamed Ahmed Bullet (there are six Ahmeds in the unit and his trainers had to distinguish among them) jokes in limited English that he doesn't like Michael Jackson. But, he says before emptying his mounted machine gun into the desert, he does like US Special Forces.

These men have been in the fight against ISIS for months. Their main question as they enter this closing chapter of the war: What level of bloodshed will they have to cause to defeat the enemy?

Reminders of ISIS

A room in a house in the town of Bazwaya, near Mosul city, was used as an ISIS classroom. The Arabic writing on the whiteboard is a lesson about how to use grenades.

The town of Bazwaya itself is still haunted by its recent occupiers. An old school was used to teach grenade tactics, with instructions written on the whiteboard. Its doorbells are marked by graffiti that bans "the strike force" from entering, and half-prepared food rots in the kitchen. Nobody left here slowly.

Elsewhere, a stolen Syrian army tank hides in the basement of a house, its ISIS driver having simply reversed it into the building basement to keep it out of the view of drones. A Predator had flown above moments earlier, a reminder of the Coalition's presence.

The town is split along its main road by a huge tunnel, wide and tall enough to drive a motorbike along. It was dug by an excavator and then torched by the Iraqi special forces. As we are there, soldiers discover newer tunnels, some with shelters attached.

Sniper fire

A section of an ISIS tunnel at the town of Bazwaya destroyed by a unit from the Golden Division, an elite Iraqi forces division.

At one outpost, Alpha Company has a snapshot of how resilient their foe can be. Capt. Ala, using his scope, can regularly see his adversary hundreds of meters away behind sandy berms. Mustafa Sniper, as he is known, checks the top of the berm, and suddenly several rounds crack through the air above their heads. ISIS fighters are using a truck that allows them to pop up over the berm, open fire, and then repeat the procedure from another position moments later.

The soldiers, visibly nervous owing to how close their adversary is, try to fire back, but the moving target slows progress. "Where is the vehicle?" one shouts, as he loads a heavy machine gun. The exchange continues for 10 minutes.

Death at dusk

At dusk the unit takes its hardest blow. At one point tracer rounds race fiercely back and forth across the street we are based upon. It was impossible to tell which blast hit Ala's men, but several rockets struck a room where the unit slept, making the largest contribution to a death toll of 14 that night.

One witness described how the strength of the blast tore limbs from bodies. Another witness said he stumbled over body parts when he entered the room in the dark.

That night we observe the wounded rushed back and treated on a large carpet pad outdoors near the base. Many dead, in blankets in the back of pickup trucks, race past us. The Iraqi army, like many military services, does not want its casualties filmed.

'You guys are heroes'

The losses leave the unit part furious, part numb. Hussien races to the front to try to bolster the defenses. Ahmed Bullet walks silently around the base, his cheerful nature subdued. An argument erupts among some soldiers about which radio channel they were meant to be on.

Once the gunfire slows, Hussien returns to his men and tries to raise morale. He is handed the weapons of the fallen and asks for their body armor. He puts his hand on Ala's shoulder and tells his men: "You guys are heroes, and none of you should be affected by this. Those suicide bombers are nothing."

It is a moment of great loss, tempered by grief for those already gone in previous battles and the knowledge that this comes 2 kilometers from Mosul's city limits, with another 7 to go before the city center.