Sgt. Ahmed Abdelaziz, with Iraq's special forces, has been almost continually deployed fighting the Islamic State group ever since the militants overran nearly a third of Iraq in the summer of 2014. Now he's on the front lines of Fallujah, a city that was declared "fully liberated" on Sunday by the commander leading the fight against IS.

Abdelaziz has with him what he always brings into battle: a photo of his brother.

In this Wednesday, June 8, 2016 photo, Sgt. Ahmed Abdelaziz, 29 of Iraq's elite counterterrorism forces shows an Islamic State video of his brother's death, at a battle position on the southern edge of Fallujah, Iraq. Abdelaziz, has been almost continually deployed fighting the Islamic State group ever since the militants overran nearly a third of Iraq in the summer of 2014. Now he’s on the front lines of Fallujah, a city declared “fully liberated” on Sunday, June 26, 2016 by the commander leading the fight against IS. Abdelaziz has with him what he always brings into battle: a photo of his brother. (AP Photo/Maya Alleruzzo)

It's not a smiling family portrait. It is a picture on his mobile phone of his brother Saad's body among hundreds of captured Iraqi troops killed in a 2014 massacre carried out by the jihadis. IS killed more than 1,000 soldiers from Camp Speicher at a nearby Saddam Hussein-era complex of palaces in the city of Tikrit, north of Baghdad.

At first, Abdelaziz hadn't been sure of his brother's fate, but his worst fears were confirmed when IS released a video of the massacre and he recognized Saad in it. On his phone, he flipped through a series of stills from the video, saying the grisly images are reminders of his purpose in the fight.

Adding to a string of territorial victories against IS over the past year, Iraqi fighters on Sunday entered the last IS-held neighborhood of Fallujah and declared the city "fully liberated."

In this Wednesday, June 8, 2016 photo, Sgt. Ahmed Kamel, 26, of Iraq's elite counterterrorism forces, rests during the midday heat at a battle position on the southern edge of Fallujah, Iraq. He has three tattoos: the name of his brother, Saadi, who was killed by the Mahdi Army in 2008, the name of a comrade, Namar, who was killed fighting the Islamic State group; and the Iraqi flag. A senior Iraqi commander declared that the city of Fallujah was "fully liberated" from Islamic State group militants on Sunday, June 26, 2016 after a more than monthlong military operation. (AP Photo/Maya Alleruzzo)

"The fight in Fallujah is over," the head of the counterterrorism forces leading the operation, Lt. Gen. Abdul-Wahab al-Saadi, said on Iraqi state TV, surrounded by flag-waving soldiers. The victory marked a new stage in a grueling, more than monthlong operation. Al-Saadi said his troops would now start clearing the bombs planted on Fallujah's streets and in houses by the retreating militants.

As the fight against IS in Iraq enters its third year, the long back-to-back deployments are wearing many units in the country's fractured military thin. The mounting casualties among Iraqi forces have made the fight increasingly personal for those who remain.

In a unit stationed nearby in southern Fallujah, Sgt. Ahmed Kamel, 26, said he also brings the memory of lost loved ones to the fight with him.

On his right arm is the name of his brother Saadi tattooed in English cursive script. Kamel's brother was killed by the Mahdi army, a Shiite militia run by powerful cleric Muqtada al-Sadr, in 2008. Kamel's right arm bears the name of a fallen comrade: Namar. He died fighting the Islamic State group.

Patches and a Shiite pin adorn the body armor belonging to a soldiers from Iraq's elite counterterrorism forces during a military operation to oust the Islamic State group from Fallujah, Iraq. A senior Iraqi commander declared that the city of Fallujah was "fully liberated" from Islamic State group militants on Sunday, June 26, 2016 after a more than monthlong military operation. (AP Photo/Maya Alleruzzo)

At positions on the operation's front lines, Iraqi troops carry a variety religious objects and good luck charms into battle.

"Most people in Iraq, they just have faith in God and they don't feel like they need things like this," said 1st Sgt. Muayd Saad, explaining why some of his friends who aren't in the military don't understand why his considers the watch his wife gave him on their anniversary to be good luck.

"In the whole fight against IS, I have never taken it off, not even to sleep," he said.

Stationed at the nearby Camp Tariq, Pvt. Mustafa Muhammed Saadoun, 21, wears a wolf's tooth on a necklace. He says the charm makes him stronger and less fearful.

First Sgt. Malik Jaber keeps a strip of green fabric from the revered Imam Abbas shrine in Karbala tied to the shoulder of his body armor. He says he credits the holy object with saving his life when the Special Forces were fighting IS in Beiji, the central Iraqi town that is also home to a key oil refinery.

"I touched this cloth and I prayed and that's when the airstrike hit," Jaber says. The airstrike by the U.S.-led coalition took out the small IS unit that had him and a dozen other Iraqi troops pinned down inside a house.

"This time it will keep me safe again," Jaber said, "God willing."

In this Wednesday, June 8, 2016 photo, 1st Sgt. Malik Jaber, from Iraq's elite counterterrorism forces wears green cloth from the revered Imam Abbas shrine on his body armor, at a front line position on the southern edge of Fallujah, Iraq. He says he credits the holy object with saving his life when the Special Forces were fighting Islamic State militants in Beiji, the central Iraqi town that is also home to a key oil refinery. “This time it will keep me safe again,” Jaber said, “God willing.” A senior Iraqi commander declared that the city of Fallujah was "fully liberated" from Islamic State group militants on Sunday, June 26, 2016 after a more than monthlong military operation. (AP Photo/Maya Alleruzzo)

In this Wednesday, June 8, 2016 photo, Sgt. Majid Rahim, 26, of Iraq's elite counterterrorism forces shows his dog tag and a special forces pendant at a battle position on the southern edge of Fallujah, Iraq during a military operation to oust Islamic State militants from the city. A senior Iraqi commander declared that the city of Fallujah was "fully liberated" from Islamic State group militants on Sunday, June 26, 2016 after a more than monthlong military operation. (AP Photo/Maya Alleruzzo)

In this Tuesday, June 7, 2016 photo, Cpl. Mustafa Saada, 25, of Iraq's elite counterterrorism forces shows an Islamic prayer book he carries as a good luck charm at Camp Tariq outside Fallujah, Iraq. After a string of territorial victories against Islamic State militants over the past year, a senior Iraqi commander declared that the city of Fallujah was "fully liberated" from Islamic State group militants on Sunday, June 26, 2016. (AP Photo/Maya Alleruzzo)

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Text from the AP news story, AP PHOTOS: Iraqi special forces share treasured possessions, by Susannah George and Maya Alleruzzo.

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