The French soldiers seeking out jihadists in central Mali's savannahs were prepared for the sandstorms, the thunderstorms, the lack of anything resembling a road, and the need to tow vehicles whose wheels kept getting stuck in floodplains.
They knew getting information out of terrified villagers would be difficult.
But as the multi-week operation wore on in Gourma district, where 400 French troops and 100 allied Malians searched for 50-odd jihadists they estimated were hiding in the shadows, the obstacles kept piling up.
First, there were the storms, forcing them to abandon supper, pack up their mosquito nets and sleep contorted in their vehicles. Then up at 3 a.m. for a mission that couldn't start because the weather had grounded their helicopters at base.
Then, flash floods turned sandy ground to sludge and burst the wadis so only their newly deployed tracked fighting vehicles could cross.
Then they reached the thatch-and-wood villages where they suspected jihadists were hiding. Men tended cows. Women pounded millet. Everyone smiled. And nobody told them anything.
"We're not going to resolve this in a day," said David, the commander of the French forward base near the town of Gossi.
French military rules permit publication only of his first name.
"This is going to take some time."
Efforts led by France to stop a region on Europe's doorstep becoming a launchpad for attacks at home are increasingly trapped in an endless cat-and-mouse game with well-armed jihadists, who know the terrain and hide easily among civilians.
On a rare reporting trip with the French troops into central Mali, Reuters journalists saw first-hand why a five-year-old mission - initially planned as a short-term stopgap to hand over to local forces - may have many more years left to run.
The 4,500 French troops deployed in this patchwork of former French colonies for Operation Barkhane face huge logistical challenges in hostile terrain. Hardest of all, they rely on the cooperation of a civilian population spread thinly across vast and remote spaces, often either sympathetic to the Islamists or terrified of informing on them.
In Gossi, a haven for Islamic State fighters next to the borders with Burkina Faso and Niger, the town's local government councilor had fled after being threatened and was now sleeping in the Malian base, said David, the French base commander.
Operation Barkhane was launched in the wake of Operation Serval, a French offensive that pushed back Tuareg rebels and allied Islamists from northern Mali's vast desert in 2013.
While Serval had brought moderate stability to northern Mali, unrest had spread to the country's more populated center, with attacks also reaching neighboring Burkina Faso, Niger and even Ivory Coast.
With no end date announced at its launch, the follow-up operation would try to stabilize countries in the region by assisting their governments in a West African anti-terrorism force. Five years on, no end is in sight.
"We have a dogged adversary, who is tough, drawing from a breeding ground that is favorable to him because the population is isolated," Colonel Nicolas James, Commander of Desert Tactical Croup Belleface, told Reuters at its base in Gao.
On the first day of one mission, in 40 degree Celsius (104 F), the French soldiers arrived in a hamlet 10 kilometers north of Ndaki town, next to a small wood where suspected jihadists had been seen fleeing earlier.
They separated the women and children outside a thatched dome where camels chewed cud. They searched the men, took their smartphones and copied them onto a computer. One contained incriminating jihadist propaganda.
'People will come and kill her'
"Is this your telephone?" a soldier asked the suspect, and he nodded. They fingerprinted him, but with just circumstantial evidence, they let him go.
"I'm sure he's a jihadist," a French soldier guarding him later whispered. "He's making fun of us."
An elderly man in the flowing robes common to the Fulani people spread across the region brought out some fresh milk as a gesture of hospitality. Only two tried it, before they moved on to the next village.
That night it rained hard, so the next afternoon a logistics team spent all day towing vehicles out of mud. The mission set off before noon. When the troops returned nearly nine hours later, they'd covered just 5 kilometers.
At one stage, they heard reports of an armed group heading toward them. War planes were called in to scare the fighters off. One unit wanted to check a forest where weapons had been abandoned, but the troops were still stuck towing vehicles.
The next morning, a joint Malian-French mission visited a Fulani village next to woodland where they had spotted some men fleeing. The village chief, a bearded man with a green scarf and sky-blue robe, denied seeing any armed men.
"They want to talk to us but they are afraid," Malian military police unit Captain Balassine later told Reuters.
"The other day we were talking to a young girl," he continued. "First she lied. Then she said she was scared of talking because, after we leave, people will come and kill her."