An estimated 14 million Shia pilgrims thronged Iraq's holy city of Karbala on Friday to mark the annual Arbaeen commemoration, as Baghdad looks to wipe out the Islamic State (ISIS) group that has targeted their branch of Islam.
Arbaeen is one of the biggest religious festivals on earth and marks the end of the 40-day mourning period for the seventh-century killing of Imam Hussein by the forces of the Caliph Yazid - a formative event in Shia Islam.
Under tight security, thousands of worshippers crowded into the golden-domed mausoleum where the Prophet Mohammed's grandson is buried, Karbala's religious authorities said, beating their chests in unison against a background of religious recites.
Imam Hussein's martyrdom in the Battle of Karbala in 680AD was part of a fierce dispute over who should succeed the Prophet, which eventually developed into a bitter schism between the Sunni and Shiite branches of Islam.
Tens of thousands of security personnel and Shia militiamen were deployed, as in past years, around the perimeters of the sanctuary as well as on all roads leading to Karbala, about 80 kilometres southwest of Baghdad.
The expulsion of IS from Iraqi cities has added an extra dimension to this year's pilgrimage, as the Sunni militant group has repeatedly targeted Shia. Last year, a suicide bombing killed at least 70 mainly Iranian worshippers returning from the commemoration.
The militants have seen their self-styled "caliphate" disintegrate on the battlefield, and are currently fighting to hold a last pocket of territory in Iraq on the Syrian border.
'Finished with ISIS'
Believers from across the Middle East and beyond have made the pilgrimage to Karbala.
Shia Muslims make up some 60 percent of Iraq's population and ahead of the peak of the commemorations local governor Aqil Tourihi told AFP that over 10 million Iraqis had arrived.
More than two million Iranian pilgrims also crossed the border into Iraq for Arbaeen, an Iranian official said.
"The conditions are perfect, above all in terms of catering for pilgrims and security," Kuwaiti pilgrim Fadel Yaqoub told AFP.
The overall attendance appeared down on the roughly 17 to 20 million people estimated to have attended Arbaeen in 2016.
Helicopters flew overhead to ensure security in the city, located some 300 kilometres southeast from where Iraqi forces are battling to snuff out IS.
Bandar al-Hamami said he had walked some 350 kilometres with his family from their home in the southern city of Nasiriyah.
"Thanks be to God, we are finished with ISIS," he said.