>>NARRATOR: Tonight on Frontline, two enemies face each other in a brutal civil war.

On one side, a young rebel soldier fighting to the death to bring down the regime of President Bashar al-Assad.

>>(translated): My greatest joy will be to become a martyr, and for Syria to be liberated.

>>NARRATOR: Facing him, a career soldier, determined to preserve the Assad regime.

>>(translated): We are all martyrs in the marking, to keep our country safe.

>>NARRATOR: Two countrymen, now enemies, in a conflict increasingly driven by hatred.

(explosion) >>NARRATOR: With unprecedented access to both sides, Frontline journeys deep inside Syria to reveal a war that is reshaping the Middle East, in "Syria Behind the Lines."

>>NARRATOR: The Orontes River Valley tells the story of Syria.

It reveals a warring nation that is breaking apart.

In this valley, neighbor is fighting neighbor.

Every day is a struggle to survive.

A land where regime and rebels are fighting to the death.

This is the story of the people who live and fight on both sides of the front line-- neighbors now divided by religion, ideology, and the river that runs between them.

Ahmad is 20 years old, and works in his dad's garage.

Nine months ago he defected from the regime police force to join the rebel Free Syrian Army.

>>(translated): I was a policeman.

We were sent out to quell the protests, and some of us would open fire on demonstrators.

But I used to hide.

I'd throw my bullets away.

Here is my photo.

I looked evil when I was serving the regime.

I was full of hatred.

Now I look better.

This photo was taken after I joined the Free Syrian Army.

This is the real me.

The regime used to force me to shave my beard every day.

When I defected, I started to grow it.

I wanted to change my look while fighting with the rebels.

>>(translated): He's just showing off.

It's just a fashion.

It's not really him.

He even struggles to read the Koran.

I'm not happy about it.

I want him to pray but he doesn't.

He can do what he wants.

>>NARRATOR: In the center of Ahmad's village is the local office of the Free Syrian Army.

These men were all born in this valley, and like the majority of Syrians are Sunni Muslims.

They're determined to oust President Bashar al-Assad from power.

>>(translated): We want a democratic system, with a government elected by everyone in Syria.

This would be better than the Assad family.

We are in the town of Kansafra.

This town is a stronghold of the Free Syrian Army.

It was liberated from Assad's army more than three months ago.

>>NARRATOR: The army of the Assad regime has been pushed back across the valley to the other side of the Orontes River.

Ahmad's village is well within range of their artillery.

Shells and mortars are routinely fired into this village.

>>(translated): God willing, Bashar al-Assad's army can't get in here.

We run things here now.

>>NARRATOR: Doctors and nurses are ordered to report immediately to the local hospital.

Ahmad is already there, using his phone to film casualties.

>>(translated): I ran to the area to see who was injured, to see how I could help.

These people's lives are over.

This is what God had written for them.

I just despaired, and thought it was time that Arab countries felt our suffering.

>>NARRATOR: Ahmad and the people of his village have witnessed these scenes many times, fearing they will be next.

Today, it's Mohammed Mattar who has lost members of his family.

>>NARRATOR: Mohammed is surrounded by the bodies of three of his nephews.

They were killed 20 minutes ago by a government shell.

Inside the hospital are more of Mohammed's relatives.

>>NARRATOR: Mohammed's brother Mahmoud was injured while rushing his grandchildren into the house.

Minutes later, he died.

Mahmoud's son and his grandson are in the room next door.

With limited power and dwindling medical supplies, the surgeons are convinced they can do nothing for them.

>>NARRATOR: Six members of Mohammed's family are now dead or dyin The bodies are driven to the nearest mosque.

The bodies are driven to the nearest mosque.

Like many in these villages, Mohammed is a refugee who's fled the fighting in the nearby city of Muraat al Numan.

He wants to return there to bury his relatives, but the ten mile journey is too dangerous, and no driver will take him.

>>NARRATOR: They must be buried here, far away from home.

>>NARRATOR: Day and night, the shelling and rocketing of rebel-held villages continues.

Ahmad has filmed the aftermath of government shelling many times.

>>(translated): We Sunnis fear God.

We wouldn't take a human life for no reason.

Unless people are armed and attack our homes and kill us and our children.

We only retaliate against the army units that shell our homes and civilians.

That's the only time we kill the regime's soldiers.

>>NARRATOR: Across the river are regime forces, usually off limits to Western media.

Their positions along the 40 mile valley defend Syria's Alawite heartland.

This army checkpoint faces Ahmad's village, and is one of the launching sites for regime attacks.

The platoon commander is Lieutenant Ali Ghazi.

>>(translated): We are the Syrian Arab Army, and our duty is to defend this homeland, to protect unarmed civilians, and to attack militants and destroy the armed mercenaries.

>>NARRATOR: Rebel-held Sunni villages are less than a mile away.

This is President Assad's front line.

>>(translated): There are a lot of armed groups over there.

They're particularly active at night or at dawn, when they're preparing to carry out armed attacks.

There used to be a sniper in the dome of that mosque.

One of my soldiers was shot in the chest by this sniper.

They were using armor-piercing bullets, but we dealt with the threat.

>>NARRATOR: Ali is a career soldier, and engaged to be married.

But for the last two years he's been away fighting in some of the toughest places in Syria.

>>(translated): A lot of my colleagues have been killed.

Around 30 have been killed.

Two or three were officers in homes.

This is my duty, my job.

I am dedicated to my country.

We are all martyrs in the making to keep our country safe.

To preserve this state, and to protect its residents and its unarmed civilians.

>>NARRATOR: Lieutenant Ali and his soldiers are protecting this loyalist village, Aziziya.

Like President Assad and Lieutenant Ali, the villagers on this side of the valley are nearly all Alawite, a religious sect whose faith is loosely rooted in Shia Islam.

They're a minority in Syria, but have dominated the country for over 40 years.

Aziziya receives sporadic fire from nearby rebels.

As in many poor Alawite villages, most men are away, fighting in Assad's security forces.

Many Alawites believe that the fall of the regime would lead to their death at the hands of the rebels.

Everyone at the public high school knows that the senior boys may soon be drafted.

>>NARRATOR: For generations, the Alawites of Aziziya had lived peacefully with the Sunnis in the valley, even during the first year of the uprising.

But as the revolution entered its second year, neighboring Sunnis began weekly demonstrations calling for the overthrow of President Assad and his regime.

Watching the demonstrations was local Alawite politician Bahjat Hamdan.

>>(translated): Most of those areas with different faiths have been incubating environments for groups who have an extremist ideology.

It was a plan.

Weapons were brought in a long time ago.

It was all planned.

The lads here had been preparing in case the village was attacked.

>>NARRATOR: In May last year, as violence spread across Syria, fighting finally broke out between the Alawites of Aziziya and their Sunni neighbors.

>>(translated): We were with some young men, not many of us.

The attackers were in the hundreds, about 700 gunmen.

>>NARRATOR: Mohammed Mahmoud is part of an Alawite militia that protects the village.

>>(translated): As the attack intensified and the number of the terrorists increased, we retreated.

So they came in here and burned everything.

You can see the fire damage.

>>NARRATOR: He's convinced that his Sunni neighbors have been infiltrated by terrorists with extreme religious beliefs.

>>(translated): They are planning to wipe us out.

They don't even think of us as humans.

In their books they call our sect the "Akbiya."

The "Akbiya"are insects that should live underground.

We cannot surrender to this idea, because we are talking about genocide.

There can be no negotiating with this extremist ideology.

You either win or you die.

The terrorist leading the attack, he was killed over there.

His blood was all over the door.

I killed another guy over here next to this door.

The door over there.

>>NARRATOR: When the battle was over, at least five people lay dead, scores of houses were destroyed, and the valley was divided.

Alawites and the regime army took control of this side.

The Sunnis abandoned their homes and fled to the other side of the Orontes River.

>>(translated): This is an empty area, no one lives here.

The residents fled because of the militants.

There's nobody.

It's dangerous ahead.

That's where most of the gunfire comes from.

There's a water tank, and we often get snipers positioned up there.

This is the front line.

It's a dividing line.

There are no armed militants west of here.

The area to the west is almost safe.

The militants want to break through here and push inside.

>>NARRATOR: The front line dividing Alawites and Sunnis means that hundreds of farmers now have crops in the no-man's-land between the two warring sides.

>>(translated): How can I tell if it's a gunman or a farmer coming to plow his land?

In this conflict we can tell the difference between a gunman and a farmer.

We only open fire if we see him carrying a gun.

>>NARRATOR: From here, rebel territory is less than a mile away, on the other side of the river.

In the Sunni village directly opposite the checkpoint, local farmer Mohammed Hamadeh prepares to check his crops.

Mohammed's farmland lies on the other side of the river in what is now no-man's-land.

The road leads directly to the Aziziya checkpoint, and has been closed since the fighting broke out in the valley.

>>(translated): I grow sugar beets.

But for the past year I haven't been able to harvest them.

The land is only 400 meters from the checkpoint.

There's the checkpoint over there.

Anyway, here are the beets.

Look at this.

Ruined.

We planted these a year ago.

We're ruined, totally ruined.

(gunfire) (gunfire) They keep shooting at us.

They have killed shepherds and farmers before.

We don't even know who's shooting at us.

All we know is that it's coming from the checkpoint.

A long time ago, the relationship between the Alawites and Sunnis was good.

But now they don't miss an opportunity to hurt us.

It's impossible for us to live with them.

There'll be vendettas for 50 years because of these crimes.

If it wasn't for the rebels protecting us, the Alawites would come into our homes, rob us, and burn our houses down.

>>NARRATOR: As fighting continues in the Orontes River Valley, the United Nations suddenly announces that both sides have agreed to a nationwide ceasefire.

It will start tonight for the Muslim holiday of Eid.

The news surprises the fighters in the valley.

Ahmad and his commanding officer are summoned to discuss the announcement with their battalion leader.

He's one of the most powerful rebel leaders in the region.

His name is Jamal Maarouf.

>>(translated): I would love to be like Jamal.

He's a true leader.

A leader of 10,000 armed men.

Jamal Maarouf, an excellent military leader.

His brigade is made up of groups from all over Syria.

>>NARRATOR: Jamal is the commander of the Martyrs of Syria Brigade, one of the biggest factions of the Free Syrian Army.

While some rebel units contain Islamic foreign fighters, Jamal says his men are all local, and they're fighting for a democratic Syria.

He's called a meeting in a safe house deep in rebel territory, and is clear on how he will respond to the United Nations truce.

>>(translated): We are not going to have a truce with killers and criminals.

No way.

>>(translated): These declarations are being made by people who live abroad, people who don't represent the revolution on the ground.

I contacted all the combat divisions on the ground by Skype and phone.

They literally said that they do not want to commit to this truce.

Tomorrow we will hit the checkpoint at Wadi Daif.

Be ready at 5:30 a.m. Pray, and then come.

>>NARRATOR: Jamal says the attack will bring democracy and justice one step closer.

>>(translated): Syria is for all Syrians.

If the regime falls, we vow to protect all the peoples of Syria.

Only killers will be held to account.

We will only hold to account people who have the blood of innocents on their hands.

The Alawites have the right to live in Syria.

No one should be excluded from society.

>>NARRATOR: The next morning, just as the United Nations truce begins, Ahmad and his comrades prepare for battle.

>>(translated): We always try and pray before battle.

It makes us stronger.

We've realized that only God will help us.

So we ask God for the strength to attack more checkpoints.

>>NARRATOR: Ahmad is going to attack a large government base at Wadi Daif.

It's a major launching point for artillery attacks in the region.

It also protects the regime's main supply route from the capital, Damascus, to Syria's embattled second city, Aleppo.

>>NARRATOR: For weeks, they've been besieging the base at Wadi Daif.

The fighting has been intense.

The brother of rebel leader Jamal Maarouf was killed here only weeks ago.

Today they plan to storm the base and overrun it.

The fog allows them to move unseen to within striking distance.

The base lies less than a mile down this road, and is manned by up to 500 regime soldiers.

>>NARRATOR: Jamal used to be a local construction worker.

Today he claims to command over 10,000 armed rebels.

Nearly all his heavy weaponry is looted from the regime after successful raids.

>>NARRATOR: The latest addition to Jamal's armory is a stolen rocket launcher captured by Ahmad's unit.

Unfortunately, no one knows how to aim it.

>>(translated): I am always happy when I am around the Free Syrian Army.

Our morale is high.

We're happy.

We are building the new Syria.

I feel happier with each inch we liberate, and with each mission.

My greatest joy will be to become a martyr, and for Syria to be liberated.

>>NARRATOR: Despite recent offers of support, the West refuses to arm any units of the Free Syrian Army.

And these rebels are running low on ammunition.

>>NARRATOR: The attack begins, and Jamal and his commanders stay back to coordinate.

Ahmad's unit must wait as no one can show them how to use the rocket launcher.

>>NARRATOR: Within minutes, regime soldiers return fire with artillery.

>>NARRATOR: With the fog clearing and his men taking artillery fire, Jamal Maarouf orders his units to fall back.

Ahmad is told to take cover.

>>NARRATOR: Without the firepower to overrun the base, they must continue with the siege.

As the rebel fighters dig in, the Sunni villagers move out.

>>(translated): This is our time to defend the country.

I am making sacrifices for women and children, and for future generations.

Our mission is dangerous, but we must make this country safe again.

>>(translated): My soldiers put this on the wall, not me.

>>Why do you say that?

>>(translated): Because people say the army is from one sect, or that the conscripts are forced to do things like that.

And that's not true.

This army is from all parts of Syria.

We don't think in a sectarian way.

Our soldiers are from all sects.

We're an ideological army.

We all live together on this Syrian land.

We're not sectarian.

The people over there are sectarian, and we don't accept that.

>>NARRATOR: Hundreds of regime soldiers hold the front line along the Orontes River.

Lt. Ali's base is home to conscripts drawn from Syria's many minorities-- not only Alawites, but also Christians, Druze, Kurds and Turkmen.

Many of these minorities fear domination by Sunni Muslims.

But there are also Sunni conscripts here, risking their lives to defend the regime.

>>NARRATOR: Soldiers' phones are routinely monitored by the regime to limit the chance of them defecting, and to prevent them from speaking to enemies like the villagers across the valley.

They rely heavily on regime TV stations for news.

>>NARRATOR: Many are convinced they're fighting an army of foreign terrorists who are aided by the international media.

>>NARRATOR: It's three days since the attack on Wadi Daif and the collapse of the United Nations ceasefire.

On the rebel side of the Orontes River Valley, villagers are terrified of what the regime may do next.

>>NARRATOR: While Sunni villagers flee the daily threats, many more arrive every day, escaping the fighting in nearby cities.

They think that these villages are safer.

But Ahmad's village is struggling.

>>NARRATOR: The new arrivals are putting pressure on dwindling supplies of fuel, medicine and food.

>>(translated): I grew up in this valley.

I used to mix with the Alawites a lot.

We were like brothers before this revolution.

We used to go to their homes until the early hours of the morning, and they'd visit us, too.

If the Alawites don't want to fight us, then we will solve this problem peacefully.

But if they want to confront us, then we'll respond with deadly force.

>>NARRATOR: Three miles from Ahmad's village, in the settlement of al Bara, Jamal Maarouf meets his senior commanders.

They're planning their next attack on the army base at Wadi Daif.

(jet flies overhead) (explosion) >>NARRATOR: A regime jet has dropped a bomb on Al-Bara.

It's landed 300 yards from Jamal and his commanders.

They fear they are being targeted, and flee to safe houses.

The bomb has destroyed homes filled with villagers and refugees.

>>NARRATOR: A second bomb lands.

The people here are refugees who've fled the fighting in the nearby city of Maarrat al-Nu'man.

>>(translated): I felt terrible.

What can one feel, to see so many bodies?

People under the rubble, and we can't do anything about it.

No one is supporting us, and no one will.

They're just waiting for Bashar al-Assad to kill us all, and for us to wear out his army, his tanks and his aircraft in the process.

That's what the Western and Arab countries want.

Their heart isn't with the Syrian people.

They don't care about all this.

About these people that are bombed to pieces.

I don't know what I can do.

There is no power except that which comes from God.

>>NARRATOR: The next day across Syria, the regime carried out over 60 more air strikes.

Over 70,000 people have now died in Syria's civil war, many of them civilians.

Many more have been injured, and over four million Syrians are now refugees.

>>(translated): The political and military leadership in the country does not want to cause civilian casualties.

Had it wanted to target civilians, it would have killed many.

It is my moral, religious and patriotic duty to defend my home and my country.

If this is considered a crime, if defending my country is considered a crime, then I am this country's first criminal.

>>(translated): I'll feel very sad if the country stays like this.

It breaks my heart.

Before, I could travel late at night.

Syria was a very safe place.

People envied our security.

It breaks my heart.

I wish Syria could return to the way it was, the way we used to be.

>>NARRATOR: Three days after the air strikes on Al-Bara, the regime jets returned.

Ahmad had tried to film the planes on his phone.

>>(translated): I curse the father of Assad and Bashar the dog.

>>(translated): I hoped to die and become a martyr, but God was satisfied with just shrapnel in my body, thank God.

I can't move my legs.

There's a dangerous injury in my head.

Shrapnel has gone in here, and they can't get it out.

There's shrapnel in my chest, too.

They can't get it out.

My arm's been badly injured.

I can't move it.

I can't carry a weapon anymore.

>>(translated): If he was martyred, I would pick up his gun and fight in his place.

>>(translated): If anything happened to me you would kill as many people as there are stars in the sky, right?

>>(translated): I swear to God, I wouldn't just kill them with a rifle, but I would use my own teeth.

If God gave me the strength, if one day I saw Bashar al-Assad, I would drink nothing but his blood.

Not only for my son, but for all those who have been killed.

>>NARRATOR: The Orontes River Valley reveals Syria's likely future.

Whoever prevails will inherit a fractured nation, divided by religion, politics and revenge.

Captioned by Media Access Group at WGBH, access.wgbh.org >> For more on this and other Frontline programs, visit our website at pbs.org/frontline.

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