Mohammed joined the Hashed al-Shaabi paramilitary units, or "popular mobilisation" forces dominated by Iranian-backed Shiite militias, to battle IS alongside the Iraqi military and police.

But this year he also made his way to the Wadi al-Salam (Valley of Peace) cemetery in Najaf -- one of the world's largest -- to sit by the white tombstone of his son killed fighting IS jihadists.

In keeping with religious tradition, Kazem al-Aibi has already visited the tombs of relatives in his home village for the Eid holidays which started Saturday for Iraqi Shiite

The Valley of Peace cemetery in the Shiite holy city of Najaf is filled with mourners paying tribute to "martyrs" who have fallen in battles to expel the Islamic State group from Iraq's cities.

s Shiite holy city of Najaf of a loved one killed in the conflict against the Islamic State group, on September 1, 2017 (photo by: Haidar HAMDANI/AFP)

Like tens of thousands of other Iraqis, Aibi's son signed up after a call from Grand Ayatollah Ali al-Sistani, Iraq's highest Shiite religious authority, to take up arms and reverse the lightning 2014 advance of IS in north and west Iraq.

Mohammed left his village in Maysan province, in the Shiite heartland south of Baghdad, to join the Hashed and fought in several battles before he fell in Al-Miqdadiyah, hundreds of kilometres (miles) away from home.

More 'martyrs' each day

Wearing a black and white keffiyeh headscarf, the father wept openly in the cemetery which serves as the final resting place for millions and where more and more "martyrs" are being buried each day.

s Wadi al-Salam cemetery in the Shiite holy city of Najaf of a fighter killed fighting the Islamic State group (photo by: Haidar HAMDANI/AFP)

Iraqi security forces, for their part, have so far not disclosed their losses.

In the fourth year of war against IS, Iraq has announced a string of victories, most importantly the recapture of the country's second-largest city, Mosul, and the expulsion of IS this week from the town of Tal Afar.

The apparently irreversible advances on the battlefield, supported by US-led coalition air power, give at least some solace to Kazem al-Aiba.

"Inshallah (God willing), after Tal Afar and Mosul, all regions and towns will be liberated," said the man with a neatly trimmed moustache and wearing a spotless white jalabiya gown.

All around him, men and women of all ages jostled for space in the alleyways

of the cemetery in the city which is a Shiite pilgrimage destination for its shrine of Imam Ali, the revered son-in-law of the Prophet Mohammed.

Black-veiled women showing only their faces and men, often sobbing, busily clean the tombstones with water and cloths, or decorate them with flowers and posters glorifying the anti-IS fighters.

Many families have opted to have their fallen in the ranks of the Hashed forces buried in the Valley of Peace as an honour, rather than in their plots in home cemeteries.

Tombs marked "martyr" have multiplied, as have the posters of "hero fighters" showing the fallen men carrying their guns.

Outside the cemetery, where there were long lines of vans, cars and motorcycles, Abu Hussein said he had also come to visit his son's grave and was proud of "the sacrifice" he had made to retake Tal Afar.

"Ridding even a square centimetre of Iraq of the jihadists is a great victory for all Iraqis," said the man in a long black jalabiya and a keffiyeh around his neck.