But after years of digging for victory, he and his comrades have now turned their skills to civilian use: gouging out irrigation channels for farmers in the southern province of Basra.

"What I'm doing makes me happy," he said, gelled hair glimmering above his sun-browned face.

In 2014, Ali and tens of thousands of others mobilised against IS, in response to a call by Iraq's top Shiite authority, Ayatollah Ali Sistani.

They joined the Hashed al-Shaabi, or Popular Mobilisation Units, a paramilitary umbrella organisation set up to fight IS.

Aged 23 at the time, Ali left his parents and his work as a day labourer in the province of Babylon, south of Baghdad.

As he knew how to operate bulldozers and other heavy equipment, he was assigned to the Hashed's engineering corps, with its slogan: "build and fight".

In December, Iraq announced victory over the Sunni extremists of IS, but the Shiite-dominated Hashed was not disbanded.

Having proved itself as a formidable force on the battlefield, the coalition has become popular across the country, including among many Sunnis.

It now seeks to become a key political player, putting forward candidates in May elections and playing more of a role in the country's civilian affairs.

- 'Continuing the fight' -

Ali joined other Hashed engineers and drivers heading to Basra -- an overwhelmingly Shiite province with more oil resources but poorer infrastructure than any other province.

"We started fighting, now we're building, which is also a way to continue the fight," said Kazem Akram, the engineer in charge of Ibrahim's team in the Al-Qurnah district.

Further east, along the Iranian border, other Hashed teams are clearing mines, while elsewhere their excavators are building or grading roads.

Basra was the first province to see the Hashed launch such projects, but senior officials have said others may be rolled out across the country soon.

"The Hashed has a long-term strategy, relying on its personnel: engineers like me, but also doctors, lawyers, all the professionals who joined it," Akram, a father of three, told AFP.

Mohammad Karim, 24, joined the Hashed in 2015 after graduating as an engineer in Baghdad in 2015.

Unlike many young Iraqis suffering high unemployment, he says he received job offers. But he preferred to enlist in the Hashed.

After more than two years on the front, he is now overseeing the renovation of the edges of a school in Basra, a port city with more than two million residents.

"With the rain, the dirt road was muddy, there was no sewage system and the children had to wade to get to class," he said.

The Hashed has stepped into the breach, agreeing with the municipality to take over the job of rebuilding.

- Hashed 'here for us' -

From his workshop in front of the school, Abou Raed, in his 40s and in charge of 11 people, observes the machines in action.

"Basra is Iraq's cash cow: we call it the Mother of Oil, but we don't even get the most basic services," he said.

"The authorities never come here, but the Hashed, which has already spilled its blood for Iraq, is here for us."

Basra prides itself on having given up more "martyrs" in the fight against IS than any other province. Posters line the roads and monuments stand in the villages to commemorate those who have fallen in battle.

And despite the fact that the battle is over, the Hashed still has tens of thousands of members.

"All they have done and all these people, can't simply disappear," Karim said.

Hashed engineers take home around 750,000 dinars a month (a little more than $600, 480 euros), a good salary in Iraq and higher than they would earn in the public sector. They also enjoy some level of job security.

Others, Karim said, are there "because it is a humanitarian job".

"The Hashed will remain," he said.

That suits Khalil Fahd, head of the Al-Qurnah water authority. In the past two months, Hashed workers have dug about 40 kilometres (25 miles) of irrigation canals in his district.

"It's a rescue operation, the farmers are threatened by drought," he said. State authorities have neither the means, the equipment nor the men to deal with it.