When a motorbike convoy of Boko Haram fighters invaded Baga in north-east Nigeria last December, residents feared the very worst. Watching the gunmen roll in, they recalled Boko Haram's last seizure of the town in 2015, when hundreds of their men were slaughtered and their women kidnapped as “bush wives”.
This time, though, the Hells Angels' style motorcade did not bring the usual orgy of rape, murder and pillage. "They didn't beat anyone, they just said that we should stay where we were," said Mansour Yusuf, 44, a father of nine. "But they also said we were free to leave if we wanted to."
Mr Yusuf took no chances, fleeing along with thousands of other Baga residents to the better-defended town of Monguno, where Nigerian troops have dug a protective trench around the town.
That he is alive to tell the tale, however, does not speak of any new tender-heartedness on Boko Haram's part. Instead, the "hearts and minds" strategy is all part of the long-term game being played by the new Isil-allied faction of Boko Haram.
Known officially as Islamic State's West Africa Province, or ISWAP, the group has gained a firm foothold in the past year, confounding claims by President Muhammadu Buhari that the insurgency is facing defeat.
Focusing on military rather than civilian targets, they have mounted devastating, well-organised attacks on isolated army bases, including one last November in which up to 100 soldiers died.
The group declared fealty to Isil in 2015, splintering from the rival Boko Haram faction led by Abubakr Shekau, the man notorious for the Chibok schoolgirl kidnapping in 2014.
While Shekau revelled in indiscriminate brutality – he boasted of slaughtering people "like chickens" – ISWAP has tried to build turf by courting rather than cowing the civilian population.
Massacres of entire villages have been avoided, as has the use of women and children as suicide bombers. To sweeten the pill of its religious dogma, it tries to present itself as a force for equality and social justice.
"When they came into Baga, they promised that they would take the food stocks from all the influential men in the community and share it with us," said Abdullahi Mohammed, 42, another fisherman who fled to Monguno. "They said: 'the government does nothing for you, we are here to relieve your suffering'."
There are limits to the group’s charm offensive, however. Captured soldiers and civilians suspected of spying can still expect torture and execution. Last year, the group also kidnapped and murdered two Nigerian Muslims working as nurses for the Red Cross, describing them as "apostates".
One man in Monguno showed the Telegraph an ISWAP propaganda video, showing two relatives who had been kidnapped by the group during the attack on Baga. “They were working for the civilian joint task force (an anti-Boko Haram vigilante group,” he said. “They’ll probably be killed now.”
Just how close ISWAP’s links are to Isil’s core leadership in the Middle East is unclear: most experts doubt it gets much logistical help. But with Isil now in disarray in both Iraq and Syria, Nigerian army commanders claim that foreign jihadists are already swelling its ranks.
"We have battle encounters where some of the corpses we have seen on the ISWAP side have been either white or North African - I've seen a couple myself," one senior Nigerian army officer told The Telegraph. "There seems to have been influx of non-locals into this sect, and we think it may account for some of the ambitious attacks they have carried out."
Mr Mohammed and Mr Yusuf now live in tents in a vast aid camp in Monguno, along with nearly 150,000 other people made homeless by the crisis. Many have fled towns that the Nigerian army had previously declared safe.
Edward Kallon, United Nations Humanitarian Coordinator for Nigeria, said more landed was needed to build shelters and sanitation facilities. "This is crucial ahead of the upcoming rainy season, as many people are without shelter or living in overcrowded conditions that could lead to serious disease outbreaks like cholera.”
Although Monguno itself is guarded by a Nigerian army garrison, the empty desert that surrounds it is no-man's-land. For aid workers, the town is only accessible via a UN helicopter service.
The six-foot-deep trench that runs round Monguno's perimeter does not stop Boko Haram trying to attack. The night before The Telegraph visited, two local boys were reported to have been abducted.
"If you go across that trench and walk for just half an hour, you will start to meet Boko Haram fighters," Mr Yusuf added.
According to US government estimates, ISWAP now has around 3,500 fighters, mostly around the Lake Chad basin, compared to around 1,500 for Shekau's faction, which are based in the Sambisa Forest.
The strength of the two groups shows just how deadlocked the conflict has become, after a decade in which an estimated 27,000 people have been killed and two million forced to flee their homes.
The crisis is a sore point for Mr Buhari, who was re-elected in February despite criticism of his record against Boko Haram. Frontline Nigerian troops complain that vast amount of the money allocated to the war budget is siphoned off by corrupt officers, leaving them undermanned and outgunned.
On a visit to Nigeria earlier this month, the Foreign Secretary, Jeremy Hunt, warned that Nigeria was being "massively destabilised" by the conflict, and that Isil would be "looking to make their presence felt now they have lost their territory."
He hinted that Britain would offer extra military help if the Nigerian army could improve its human rights record - a view that is unlikely to have gone down well with his hosts.
Amnesty International has repeatedly accused troops of brutality and arbitrary detentions - much to the irritation of the government, which claimed last year that the rights group seemed to care more about Boko Haram than its victims. That frustration is shared by those manning the frontlines up at Monguno.
"These people who criticise us aren't up here doing the fighting, losing their lives or seeing how brutal Boko Haram are to civilians," said the Nigerian army officer. “This is a vicious war, and it isn’t fair to say that we are as bad as the militants."
By Colin Freeman