Iraqi troops advance toward the Old City in western Mosul on March 13. The battle to retake the Islamic State stronghold in northern Iraq seriously tested the mettle of the Iraqi security forces.

A view of the destruction wrought on Mosul's Old City, the final battleground in the campaign to rid the city of Islamic State presence. Iraqi Prime Minister Haider al-Abadi arrived in Mosul on July 9 to congratulate the Iraqi security forces ahead of the announcement of Mosul's liberation.

Iraqi Federal Police engage an Islamic State position with mortar fire during the battle to recapture west Mosul, April 12. Despite being completely surrounded, Islamic State fighters put up stiff resistance, forcing Iraqi security forces to engage in house-to-house fighting to retake Iraq's second largest city.

A view of the Tigris River from the compound of the Nineveh International Hotel in Mosul on June 16. The hotel was recovered by Iraqi troops earlier in the year. A screening center was established to receive the steady stream of Iraqis fleeing the fighting. Any civilians seeking refuge were first screened by Iraqi security forces searching for suspected Islamic State members attempting to escape.

A Kurdish Peshmerga fighter reacts to hits against his vehicle from Islamic State snipers located in the small town of Bartella just outside Mosul on Oct. 18, 2016. Islamic State strongholds around the city had to be cleared before the assault on Mosul itself could begin in earnest. 

Families fleeing the fighting in Mosul's Old City on July 5 take pause. In the days to come, the Islamic State would be fully driven out of the city and the reconstruction effort could begin.

A man walks by destroyed vehicles in the Old City of Mosul on July 2. More than eight months after Iraqi security forces launched a punishing operation to retake the city, Islamic State fighters prepared for their final stand across a few neighborhoods on its western side.

Omar, a young wounded Iraqi boy whose family was killed in the fighting, sits with members of the Counter Terrorism Service (CTS) as they help him escape the Old City on July 3. Iraqi forces have been closing in on western Mosul for months, but the close terrain combined with a large civilian population has made for an extremely difficult fight.

A member of the Iraqi Counter-Terrorism Service (CTS) wipes his face while standing in the turret of an up-armored vehicle parked outside the destroyed gate of al-Nuri mosque in the Old City on July 2.

Members of the Iraqi Federal Police pose for a picture with children during a celebration in the Old City of Mosul during the final stages of the grueling battle to retake Iraq's second city from the Islamic State on July 2.