People eating garbage to stay alive.

Suicides of people who can bear no more.

Their words echo the past, the ghosts of Falluja back to haunt them again.

Falluja has experienced years of constant conflict. It has suffered more than any other city in Iraq. And it is suffering again.

JUST WATCHED Iraqi forces make gains in Falluja battle Replay More Videos ... MUST WATCH Iraqi forces make gains in Falluja battle 01:45

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Iraqi forces, with the help of Shiite militias and U.S. air power, began advancing toward Falluja on May 23 in hopes of wresting control of the city from the clutches of the Islamic State. Falluja was the first Iraqi city to fall to ISIS fighters in 2014 and remains one of two strongholds for the extremists (the other is the northern city of Mosul).

Photos: The battle for Falluja Photos: The battle for Falluja Iraqi government forces drive their armored vehicle through a street in Falluja, Iraq, on Monday, June 27, after retaking the city from ISIS. A senior Iraqi general announced on state TV that the battle for Falluja is over as Iraqi troops retook the final ISIS holdout in the city. Hide Caption 1 of 29 Photos: The battle for Falluja Supplies are lined up at a camp for displaced civilians on Saturday, June 25. Hide Caption 2 of 29 Photos: The battle for Falluja Iraqi security forces evacuate an injured soldier during fighting with ISIS militants on Wednesday, June 15. Hide Caption 3 of 29 Photos: The battle for Falluja Iraqis who have been displaced from their homes peer out of a tent at a camp outside Falluja on Tuesday, June 14. Hide Caption 4 of 29 Photos: The battle for Falluja Smoke rises after airstrikes by U.S.-led coalition warplanes on Sunday, June 12. Hide Caption 5 of 29 Photos: The battle for Falluja A boy sleeps in his mother's arms after fleeing from their home in Falluja on Monday, June 6. Hide Caption 6 of 29 Photos: The battle for Falluja Smoke rises on the front line of fighting between ISIS militants and pro-government Iraqi fighters on Sunday, June 5. Hide Caption 7 of 29 Photos: The battle for Falluja Pro-government forces and Shiite militia fighters fire rockets toward ISIS fighters in Falluja on Saturday, June 4. Hide Caption 8 of 29 Photos: The battle for Falluja Iraqi soldiers help civilians from a vehicle outside a camp near Falluja on Friday, June 3. Hide Caption 9 of 29 Photos: The battle for Falluja Internally displaced civilians flee their homes after crossing the Euphrates River outside Falluja on Thursday, June 2. Hide Caption 10 of 29 Photos: The battle for Falluja Iraqi counterterrorism forces face off with ISIS militants in Falluja's Nuaimiya neighborhood on Wednesday, June 1. Hide Caption 11 of 29 Photos: The battle for Falluja Blindfolded men get led to a bus after being detained during the fighting on June 1. Hide Caption 12 of 29 Photos: The battle for Falluja A member of pro-government forces fires at a front line in the Albu Huwa area south of Falluja on June 1. Hide Caption 13 of 29 Photos: The battle for Falluja Grenades and shells lie on the ground in Falluja during fighting between Iraqi forces and ISIS on June 1. Hide Caption 14 of 29 Photos: The battle for Falluja Smoke rises as Iraqi forces face off with ISIS militants on the southern edge of Falluja on Tuesday, May 31. Hide Caption 15 of 29 Photos: The battle for Falluja Iraqi forces gather ahead of an operation to retake Falluja on Sunday, May 29. Hide Caption 16 of 29 Photos: The battle for Falluja Pro-Iraqi government fighters carry ammunition in the village of Harariyat on Saturday, May 28. Hide Caption 17 of 29 Photos: The battle for Falluja A police officer places an Iraqi federal police flag next to a Shiite militia flag outside Falluja on May 28. Hide Caption 18 of 29 Photos: The battle for Falluja Iraqi government forces engage with ISIS fighters near the village of al-Sejar on Thursday, May 26. Hide Caption 19 of 29 Photos: The battle for Falluja A pro-government fighter rests after battling ISIS near al-Sejar on May 26. Hide Caption 20 of 29 Photos: The battle for Falluja Iraqi government forces advance near al-Sejar on May 26. Hide Caption 21 of 29 Photos: The battle for Falluja Iraqi security forces surround an ISIS drone that was shot down outside Falluja on May 26. Hide Caption 22 of 29 Photos: The battle for Falluja Iraqi government forces take position east of Falluja on Wednesday, May 25. Hide Caption 23 of 29 Photos: The battle for Falluja A pro-government fighter holds position in the village of al-Shahabi, east of Falluja, on Tuesday, May 24. Hide Caption 24 of 29 Photos: The battle for Falluja Iraqi government forces join an operation in al-Shahabi on May 24. Hide Caption 25 of 29 Photos: The battle for Falluja Pro-government forces advance toward Falluja on Monday, May 23. Hide Caption 26 of 29 Photos: The battle for Falluja A fighter with the Badr Brigades, a Shiite militia, takes an ISIS flag down outside Falluja on May 23. Hide Caption 27 of 29 Photos: The battle for Falluja A fighter from a Shiite militia takes a combat position outside Falluja on May 23. Hide Caption 28 of 29 Photos: The battle for Falluja Iraqi Shiite fighters fire artillery near Falluja on May 23. Hide Caption 29 of 29

It is the third major battle for Falluja since the U.S.-led coalition invaded Iraq 13 years ago. This is a city that has known little peace since then, a place that for the most part has been sealed off from the rest of the world.

Aid groups warn of a "human catastrophe" in the making. They report heavy shelling and say 20,000 of the 50,000 people trapped in the city are children. There are reports, too, of the executions of boys and men who refuse to fight with ISIS. Food and medicine are scarce.

Falluja's story is a long and sad one, but it's important to know it to understand the bloodshed of today.

Before it gained notoriety as hell on earth, Falluja was called the city of mosques and minarets. By some counts, as many as 200 dotted the landscape, though few are left standing. Some of the most intense battles have been fought around mosques that insurgents used as havens.

A British plane mistakenly bombed a market in Falluja during the Gulf War in 1991.

Long before the Americans came, the people of Falluja stood up against the British, who invaded and occupied Iraq during World War I. History books tell the tale of Falluja's Sheikh Dhari who brazenly killed a senior British officer and sparked an uprising against colonial rule. Decades later, Dhari's grandson ascended to prominence as a Sunni cleric and a vocal opponent of U.S. actions.

Under Sunni dictator Saddam Hussein, Falluja had grown into a sizable city of 300,000 and gained importance for its strategic location, just 40 miles west of Baghdad and on the road to Jordan and Syria.

It was from that road that I first saw Falluja in 2003, days after the invasion of Iraq began. I knew little about Falluja then: only that it was as ancient as Babylon and was the most populated city in Anbar province. And that in the fourth week of the 1991 Gulf War, a British Tornado airplane mistakenly bombed a market, killing 130 civilians and sparking local anger.

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The drive to Baghdad took me through Anbar province, heavily Sunni and tribal territory. Falluja had been as loyal to Hussein perhaps as the toppled leader's hometown of Tikrit. Many Fallujans lost their jobs after the United States took control, disbanded the Iraqi army and sacked Baath Party members from civic institutions.

Local resentment of foreign forces was evident from the day soldiers of the Army's 82nd Airborne Division arrived in Falluja in late April 2003. It boiled into rage after U.S. soldiers fired on a demonstration against their presence and killed 17 people.

From the very start of the Iraq War, Falluja was a bastion of Sunni dissent that would give rise to a violent insurgency, the birth of al Qaeda in Iraq and now the Islamic State.

Falluja's watershed moments came in 2004, when four American contractors were killed in chilling fashion. The men, employees of the former Blackwater security firm, were ambushed and killed by an angry Iraqi mob. Their bodies were mutilated and burned and two were hung from the steel girders of a bridge over the Euphrates. One man held a sign that said: "Falluja is the cemetery for Americans."

The images elicited shock and outrage from the American public and changed the course of the war.

The U.S. military launched two major offensives on the city in 2004. The second, Operation Phantom Fury, became the bloodiest battle of the Iraq War, securing its place in Marine Corps. legend alongside Iwo Jima in World War II and Hue in Vietnam.

U.S. journalists embedded with Marine units gave terrifying accounts of the hunt for insurgents: navigating dark maze-like lanes laden with explosives and snipers, jumping from roof to roof, blasting through doors and windows and pounding the city with artillery shells.

Falluja was pulverized by more than 300 bombs and 6,000 rounds of artillery during the six weeks of battle.

During the second battle of Falluja in November 2004, a Marine writes a message on the bridge over the Euphrates where the charred bodies of American contractors were hung.

At its end, more than 80 Americans and thousands of Iraqis were dead. The destruction was apocalyptic.

More than half of Falluja's 39,000 homes were damaged. There was no electricity, water or sewage disposal. Anyone who could flee did so. Then, as now, about 50,000 people remained trapped in the city. Fallujans' accounts of the violence then sound eerily similar to their descriptions now.

CNN correspondent Arwa Damon covered the Marine offensive in Falluja in 2004 and, on the 10th anniversary of the war, reflected on what she had experienced.

She recalled seeing a red shoe smaller than her hand, adorned with a pink ribbon and bow:

"The shoe lay in a rubble-strewn yard amid the mustard yellow debris of a partially destroyed single-story home in a poor part of the city. My world froze right then. I imagined a little girl with curly, dark brown hair, about 5 years old. I could almost hear the shouts as she and other children ran around the yard playing joyfully."

Damon never found out who had worn that shoe, or whether she was still alive. It bothers her to this day. So many died that way in Falluja -- unknown, ungrieved by the world.

"Falluja has been a graveyard. For Iraqis. For Americans," Damon told me this week as the current battle for the city raged. "I find it utterly tragic that once again, because it was abandoned, people's cries for help were not listened to."

The Pentagon declared the 2004 Falluja offensive a huge victory against terrorism. It was supposed to be the death knell for the insurgency. But it wasn't.

The Marines who fought there have mixed feelings about Falluja, given the course of events since then. Some have said they bled in vain. At the very least, they said, it is discouraging to see Falluja back in the hands of extremists.

Sunni disenfranchisement led to massive anti-governent protests in Falluja in 2013.

Author Bing West, a former Marine who fought in Vietnam and was embedded with a Marine battalion in Falluja, told me he was frustrated that the United States disengaged from Iraq after sacrificing so much. The policymakers, he said, "have let the soldiers down. They didn't show the same resolve."

"And the poor Sunnis," West said. "They have no future. I don't care who takes over the city now. They have no money. They have no hope."

There had been a sliver of hope once.

In 2007, I returned to Anbar just when many of the tribal sheiks were rising up against al Qaeda. They were fed up with the violence that ruined their cities, left their people without jobs and their children growing up without good health care and education.

The Anbar Awakening, as it was known, led to the Sons of Iraq -- tens of thousands of Sunnis who joined the fight against the militants and were a big reason for the success of the so-called U.S. "surge." But the Shiite-led government in Baghdad failed to integrate them, and the movement quickly fell apart.

I understood then the frustration of the Sunnis in Falluja, Ramadi and the rest of Anbar. First there was a foreign occupation, then sectarian war and a Shiite-led Iraqi government that many Iraq experts argue will never take Sunni interests to heart. Fallujans felt disenfranchised, abandoned.

It's not that most Fallujans accepted al Qaeda or now, the Islamic State. The extremists found power in their discontent.

I had interviewed Anda Khalaf, a former colonel in the Iraqi army under Saddam Hussein, when the Sons of Iraq movement was taking hold. He told me the insurgency was imported to Iraq by foreigners but mushroomed in Anbar because so many men were sitting at home, jobless and angry. There was nothing left in war-ravaged Falluja, but getting in and out of the city required special U.S.-issued identity cards with retinal scans.

The anger never went away.

When U.S. troops convoyed out of Iraq in December 2011, people celebrated in Falluja and burned an American flag. The scars of war were not healed, the devastation still amply evident to those who visited the city.

Two years later, in 2013, protests erupted again in Falluja, this time against the government in Baghdad. Islamic State was ready to capitalize on the heightened sectarian tensions and put out a message urging Sunnis to take up arms to fight the Shiite-dominated leadership.

A few months later, Falluja fell.

Islamic State fighters celebrate after commandeering a vehicle in Falluja. The city fell to ISIS in 2014.

I spoke this week with Ross Caputi, a former Marine who fought in Falluja and later became critical of the U.S. presence in Iraq. Caputi told me that the situation in Falluja now, as then, is simplified as a good guy vs. bad guy narrative.

"The fighting is predicated on the belief that if you eradicate every single fighter of the Islamic State, then everything goes back to a happy equilibrium in Iraq," said Caputi, who researched Falluja in the years since 2004 and launched the Justice for Falluja Project to raise awareness of the city's suffering.

"We are repeating history. A lot of the same things that happened in 2004 are happening now. It's the civilians paying the price."

I watched Caputi's documentary, "Fear Not the Path of Truth," in which he explores the atrocities of war in Falluja. Among those he interviewed was Amir Alani, a sociologist from Falluja who spoke of the British occupation and said he grew up with an understanding that foreigners who occupied his country were not welcome.

It was this historical perspective that many Americans I met in Iraq did not know. They could not understand why Iraqis were not more accepting of U.S. actions.

Sadly, very few people I spoke with about Iraq feel any hope for Falluja. Even if the Iraqi forces retake control of the city, what lies ahead for its people? With Shiite militias in the fight, there is a good chance of sectarian strife.

And who will rebuild Falluja, reduced again to rubble?

A man I once met outside of Falluja told me foreign forces had cursed his city. Life, he said, would never return to the way it was.

Falluja, it seems, is doomed to keep writing its long, sad history.