>> NARRATOR: Tonight on Frontline, two special reports from inside Iraq's besieged city of Mosul.

First... >> This is the other entrance of the building.

>> NARRATOR: Guardian reporter Ghaith Abdul-Ahad shows us the human toll of war with ISIS.

>> No one knows how many civilians have been killed in this battle of Mosul.

Not even the government know.

>> NARRATOR: And later, how Iraq's Special Operations Forces are hunting ISIS.

(automatic gunfire) (woman screaming) >> NARRATOR: And protecting those civilians trapped by the fighting.

(weeping softly) (gunfire) >> NARRATOR: Tonight, on this special edition of Frontline: two stories about survival, determination, and the battle for Iraq.

>> ISIS's so-called caliphate is under attack... >> It's been an effective summer for Iraqi forces battling ISIL fighters... >> The edge of Mosul is close... >> Iraq's prime minister says the battle to retake Mosul from ISIS is going more quickly than expected... >> Iraqi forces are saying it's going much faster than planned... >> NARRATOR: Mosul, northern Iraq.

Reporter Ghaith Abdul-Ahad is on his way to the front line.

For more than two years, this city of over a million people has been under ISIS control.

Now the Iraqi army, backed by Kurdish forces and U.S. airstrikes, is trying to retake it.

>> ABDUL-AHAD: Iraq's my own country, I lived in Iraq, I grew up in Iraq.

I knew Mosul since I was a child.

My father used to take me with him.

I walked in the old city, in the old market.

I had this connection to Mosul.

In 2016, Mosul was declared as this final battle, the final showdown with ISIS.

I went to Mosul to see if the liberation of the city will usher the end of this endless war that has been going on in Iraq since 2003.

>> NARRATOR: The operation began in October 2016, and the army quickly defeated ISIS in the villages surrounding the city.

But when they entered Mosul itself, the advance was slowed by fierce fighting.

ISIS used snipers hidden amongst the civilians to exact heavy casualties.

(gunshot) >> (men speaking Arabic) >> NARRATOR: And they began an unprecedented campaign of suicide attacks.

It is now five weeks since the battle began.

Ghaith is with the elite Iraqi Special Operations Forces, known as the Golden Division.

They're taking him to their commander in eastern Mosul.

>> NARRATOR: The route to the front line passes through areas that until recently were controlled by ISIS.

>> ABDUL-AHAD: The narrative was, the Iraqi army's moving very quickly.

ISIS lines are collapsing.

As we start driving in, you realize you're not driving through a liberated neighborhood per se, but you're driving through a battle zone.

>> NARRATOR: Unknown to the soldiers, ISIS fighters are lying in wait.

(gunshot) >> NARRATOR: Ghaith and the soldiers make it past the ISIS snipers and stop at a base the unit has set up in a local house.

>> ABDUL-AHAD: Where we are is 380 meters from one front line, 400 meters from another front line.

The fire is really close.

As we drove, even the so-called liberated neighborhoods, which we are now, is under constant fire.

A bullet whizzed over our heads.

The distance between war and civilian life is almost nonexistent.

It's kind of street by street.

>> NARRATOR: The unit's leader, Lieutenant Colonel Munthadar, is using drones to direct his men to ISIS positions.

He commands around 125 soldiers and has survived several ISIS attacks.

Munthadar has a reputation for toughness.

To his men, he is known simply as Fuladh, which means "Steel."

>> This is Gokjeli.

The radio station is here.

We want to clear all this area back to Gokjeli.

We will close this area off.

I want to secure the residential area.

These are tall apartment buildings.

So it's very hard to fight here.

>> NARRATOR: The Iraqi army has a bad reputation in Mosul.

The population here is mainly Sunni Muslim-- the army, mainly Shia.

Before the ISIS takeover, the army was accused of sectarian abuses and illegal detentions.

>> ABDUL-AHAD: The civilians, I am sure they look at the soldiers and they worry who will be detained next.

It's like two people of one nation finally meeting.

A week ago, three days ago, those people would have not imagined sitting there having a conversation with a Shia Iraqi soldier from the south.

>> NARRATOR: Munthadar says he understands the residents' fears, but he is trying to convince them that he is on their side.

>> (translated): People are starting to trust us, and they are telling us where ISIS infiltrators are hiding.

The people who've been liberated, they say the army is not sectarian.

This is not a sectarian army or a Shia army or anything of the sort.

It's an Iraqi army coming to liberate.

>> NARRATOR: But the fight has become bogged down in Mosul's densely populated neighborhoods.

>> (translated): Before one of our soldiers pulls the trigger, he needs to be aware of exactly who is in front of him.

I mean, an army can fight against a regular army in the usual way.

Tank against tank, soldier against soldier.

But what is happening here is a dirty battle.

Against dirty people.

It's difficult liberating these areas from this filth.

(gunshots in distance) >> NARRATOR: It's dangerous to stay so close to the front line at night, so Ghaith and some of the soldiers pull back.

>> NARRATOR: The soldiers seem nervous.

ISIS fighters are in the area.

>> NARRATOR: They arrive in the neighborhood where they will spend the night, and meet up with some of their fellow soldiers.

(radio beeps) >> NARRATOR: The soldiers are on the lookout for ISIS collaborators among the civilians.

They have orders from the lieutenant colonel to treat captives humanely.

But away from the fighting, one of the soldiers watches videos of ISIS suspects being tortured.

(man in video screaming) (man screaming) (man talking on radio) (man talking on radio) (man talking in video) (man screams in video) >> NARRATOR: A local family has agreed to let Ghaith and the soldiers spend the night in their house.

They are a mile back from the front line, and feel safe.

But they're wrong.

The war is about to come to them.

>> ABDUL-AHAD: I wake up early in the morning.

I went outside to the street.

And I saw the soldier across the street from me, and he shouted, "Mufakhkhakha!

Mufakhkhakha!"

"Car bomb, car bomb!"

This is the other entrance of the building.

>> Yes.

Get it quickly.

(gunshots) >> NARRATOR: An ISIS truck bomb has exploded a few feet in front of the house where Ghaith and the soldiers spent the night.

The house has collapsed.

Ghaith immediately starts filming.

He finds the soldier who warned him.

(gunfire) >> NARRATOR: ISIS gunmen are now trying to pick off the soldiers, who fire back.

>> ABDUL-AHAD: We were in the middle of this huge scene of carnage.

Everything is this dark, black, grey, mixture of concrete and burnt plastic, puddles of water, debris, burnt Humvees.

Then the civilians start emerging from the collapsed houses.

>> NARRATOR: Ghaith's colleague and producer, Josh Baker, has dug himself out of the rubble.

He will later discover he has a fractured spine.

(children crying) >> NARRATOR: No soldiers have been killed.

The civilians have borne the brunt of the attack.

Several are feared dead under the debris.

Those that survived are now homeless.

(gunfire in background) >> NARRATOR: The soldiers think the attack was meant to kill Lieutenant Colonel Munthadar.

>> ABDUL-AHAD: I think that day, we realized the complexity of the battle.

The civilians are still there.

This is a battle happening between two enemies on a land inhabited by the civilians.

No one knows how many civilians have been killed in this battle of Mosul, not even the government of Iraq.

>> NARRATOR: In the weeks that followed, Ghaith and many other journalists pulled out of Iraq, and Mosul slipped from the headlines.

In December, when Ghaith returned, Iraqi forces had made little progress and ISIS suicide bombings in Mosul had become routine.

(siren blaring) (horn beeps) (child crying) >> NARRATOR: Today, three truck bombs have detonated in a market.

The casualties are rushed to a hospital in the nearby Kurdish city of Erbil.

(child crying) (monitors beeping) >> NARRATOR: Since the battle began, thousands of civilians have been injured in Mosul.

The hospital's senior surgeon has been struggling to cope.

>> ABDUL-AHAD: So you don't have enough medicine?

>> ABDUL-AHAD: So no preparation for the war?

>> NARRATOR: These residents of Mosul have all spent more than two years living under ISIS rule.

(children chattering and yelling) >> NARRATOR: More than 160,000 people have fled the fighting in Mosul.

Many are living in camps outside the city.

Abu Yasin is a computer engineer who worked at Mosul's university.

>> (translated): Compared to home and what we have experienced, we see this camp as a blessing.

Yes, it's miserable, but it is still better than death.

>> NARRATOR: He tells Ghaith that when the Iraqi Special Forces first drove ISIS out of his neighborhood, it was a moment of hope.

>> (translated): People started making jokes, saying it's time to shave our beards.

The barbershop opened and we all went and shaved.

We were happy to see the end of the oppression.

>> NARRATOR: But then ISIS began launching suicide attacks near his home.

>> (translated): The Iraqi army is taking ground, but nobody is holding it.

So what is the use of liberating us, but then letting ISIS come back in to kill not only the army, but the people, too?

>> NARRATOR: He is now worried that even if the Iraqi army defeats ISIS, life will not improve in Mosul.

>> (translated): Yes.

What I'm hearing now, speaking to people in Mosul on the phone, is that things are changing.

The soldiers who liberated us were one thing, but those coming now are different, so people are scared.

Things could change.

People have limited patience, and time is running out.

When you feel you're being killed by the Shia militia, by ISIS, by your neighbor, by the army, what's the point of living?

You might as well join the fight yourself.

>> NARRATOR: Since the rise of ISIS in Iraq, thousands of their fighters have been arrested and detained.

Some have been taken here, to the Kurdish town of Sulaymaniyah.

Ghaith has been given permission to interview a captured ISIS fighter, with a Kurdish intelligence officer in the room.

Adil Ali Ahmed says that when ISIS took over his hometown in 2014, many welcomed them, as they were sick of the Iraqi army acting like an occupying force.

>> (translated): They came suddenly.

It was like a miracle.

They lifted all the checkpoints.

There were no arrests.

Nobody would ask where you were going.

Because of this, I became convinced and joined them.

>> (translated): I was forced to do this.

I feared them.

I had no other choice.

(siren blaring) >> NARRATOR: Kurdish authorities say he confessed to his role in the suicide attacks.

>> (translated): In the beginning, yes.

But when I started seeing death and destruction I regretted it.

If I could, I would tell the people I have hurt to take their revenge on me.

I mean... >> NARRATOR: Back in Mosul, the battle has not been going according to plan.

Lieutenant Colonel Munthadar and his unit have advanced only a mile further into the city since they were hit by the truck bomb.

>> NARRATOR: He says that more than half his men have been wounded or killed in ISIS attacks, but he remains determined to win over the local population.

>> (translated): I want my troops to make a good impression... so I win the trust of the people.

Because the people in Mosul have lost trust in the police and army units who were here in 2013 and 2014.

There were mistakes.

Mistakes were committed here that our military and civilian leaders have acknowledged.

There were abuses, there was oppression of the people.

>> NARRATOR: The commander's approach pays off.

He gets a tip from a resident that three local men are suspected of being ISIS collaborators.

Ghaith is filming as the men are being taken to Iraqi intelligence for interrogation.

(man laughing) >> (translated): We are here to bring peace and security inside Mosul and defeat ISIS.

There are two forces at work here, good and evil.

The world is divided in this way.

There are people with ISIS and there are people helping us against ISIS.

>> ABDUL-AHAD: The commander is treading on a very delicate balance, a balance between defeating ISIS, killing his enemy, and not repeating the same mistakes that led to the people of Mosul realizing that the army is a force of oppression.

In that delicate balance rests the future of Mosul and the future of Iraq.

>> NARRATOR: On the street, a local man complains to Munthadar that Iraqi forces have arrested his son.

>> NARRATOR: Suddenly, someone spots an ISIS drone armed with a grenade.

(people shouting) (explosion) (gun firing) (man talking on radio) (gunfire) >> NARRATOR: The soldiers try to shoot down the drone.

Once again, they think it was an ISIS attempt to kill Munthadar.

The grenade exploded on the spot he had been standing seconds before.

Then they spot more drones.

>> (translated): The battle for Mosul is the key to the future of Iraq.

It's an international battle.

The whole world is watching.

As long as I have the ability to help the people, I will help them.

But the enemy we are fighting is the most vicious enemy in the history of the world.

The people we are fighting, they don't believe in retreat.

They will fight to the death.

>> ISIS has destroyed much of the city... >> ...special forces now control the eastern side... >> ...a war of attrition has set... >> ...they have yet to enter the west of Mosul... >> ...once a vibrant city... >> ABDUL-AHAD: I started this journey thinking, feeling a glimmer of hope that the war might actually end after liberating Mosul, that maybe we can have a moment of peace.

By the end, because of the level of bloodshed, the level of trauma, I don't think peace will come easily.

It's not about liberating a land, it's not about capturing or defeating ISIS.

It's about how much hatred there exists in the society.

That cycle of violence, unless it's broken, I don't think we'll have peace in this country.

I'm leaving with, with far much less hope than when I started this journey.

>> NARRATOR: The Battle for Mosul goes on.

Munthadar's men, and other units of the Golden Division, face many more months of fighting ISIS.

In a city that still contains hundreds of thousands of civilians.

>> NARRATOR: Coming up next on Frontline, we go deeper into Mosul.

(missile launches) >> NARRATOR: With a special unit from the golden division, battling ISIS.

>> NARRATOR: As they advance into neighborhoods full of trapped civilians.

And struggle to tell the enemy from the innocent.

"Hunting ISIS" begins right now.

>> NARRATOR: These are the soldiers of the 1st Commando Battalion.

They are a special unit of Iraq's elite Golden Division, trained for intense urban warfare.

In the brutal battle for Mosul, the 1st Battalion is at the tip of the spear.

Their job is to push into the city, killing or capturing ISIS fighters who are hiding among the local population.

>> NARRATOR: This squad is led by 25-year-old First Lieutenant Anmar Alshamry, a Sunni Muslim from Baghdad.

(gunfire) (gunfire) >> NARRATOR: Anmar's unit pushes into the Tahrir district of eastern Mosul.

They must root out ISIS street by street in an area still full of civilians.

>> NARRATOR: Anmar leads his soldiers house to house looking for ISIS.

They don't trust the civilians-- anyone could be an ISIS sympathizer.

(shouting, crying) And the civilians fear the soldiers.

(baby crying) >> NARRATOR: Anmar's unit has pushed ISIS back and needs to establish a base in the neighborhood.

>> NARRATOR: The soldiers occupy a house and move onto the rooftop.

(distant gunfire) >> NARRATOR: They set up sniper positions to look for ISIS gunmen and suicide attackers.

Mustafa Al-Ghazi is the unit's best sniper.

In such densely populated areas, it is difficult to distinguish fighters from civilians.

>> NARRATOR: Sergeant Naif al-Qairani has served in the Iraqi army for 11 years.

He fought alongside U .S.

Marines in 2006.

This rooftop is the farthest he and the other soldiers have gotten into Mosul.

The other side of the road is ISIS territory.

>> NARRATOR: The family goes back into the house, but the soldiers spot an ISIS fighter.

>> NARRATOR: Then across the road where he was shooting, another family emerges.

>> NARRATOR: The soldiers are not supposed to let civilians inside in case they are suicide bombers, but they allow the family in.

>> NARRATOR: Forced to wear a veil in ISIS-controlled Mosul, this woman, Maryam, can now show her face in public for the first time in more than two years.

>> NARRATOR: A moment of calm.

Residents come out of hiding to greet the soldiers.

>> NARRATOR: But the soldiers still suspect ISIS fighters are hiding among the locals.

The unit arrests two men.

One of them was informed on by his wife, who said he had been fighting for ISIS.

>> NARRATOR: After questioning, the men were eventually released.

But the soldiers detain another man they suspect of being an ISIS member.

>> NARRATOR: They want to check the man's trigger finger for signs he has been in battle.

>> NARRATOR: The soldiers later handed over the prisoner to Iraq's feared military intelligence.

>> NARRATOR: Sergeant Naif's family had to flee their home after ISIS captured their town in northern Iraq.

>> NARRATOR: As the unit is pushing into a new neighborhood, they come under a surprise attack from ISIS gunmen.

(gunfire) >> NARRATOR: Then an airstrike from the U.S.-led coalition takes out the ISIS position.

In the aftermath, a disturbing scene.

The soldiers find the decapitated body of an ISIS fighter.

They say they don't know who did it.

>> NARRATOR: Inside the Humvee the soldiers listen to local ISIS radio.

It's an interview with a boy planning a suicide attack.

(screaming, gunfire) >> NARRATOR: Out on the street, an ISIS suicide bomber has broken through the unit's defenses.

(shouting) (gunfire, screaming) (screaming) >> NARRATOR: The attack came from the neighborhood they thought they had cleared.

(gunfire) >> NARRATOR: At night, ISIS uses a mosque to broadcast its propaganda, calling for more attacks.

(gunfire) (gunfire) >> NARRATOR: Early the next morning, a new wave of civilians rush to flee the city, with whatever belongings they can carry.

>> NARRATOR: The only way out is to walk.

(sobbing) >> Next time on Frontline at the height of the war on terror Guantanamo held almost 700 detainees.

Now, all but 41 have been released.

NPR correspondent Arun Rath investigates where they've gone.

>> Do you think there was a misunderstanding about the terms of your release?

>> And who's responsible now that they're "Out of Gitmo."

>> Go to pbs.org/frontline for our virtual reality film "Battle for Mosul 360" with reporter Ghaith Abdul-Ahad.

>> Two, three months since ISIS fled this area.

It was set alight by ISIS.

>> And read more of his reporting for Frontline and The Guardian.

Find out more about the making of "Battle for Iraq" in our interview with producer, Josh Baker.

Connect to the Frontline community on Facebook and Twitter, and sign up for our newsletter at pbs.org/frontline.

>> For more on this and other Frontline programs, visit our website at pbs.org/frontline.

>> Frontline's "Battle for Iraq" is available on DVD.

To order, visit shopPBS.org or call 1-800-PLAY-PBS.

Frontline is also available for download on iTunes.