KNOWING YOUR ALLIES:

This is the story of why men from all over the world have chosen to fight in a brutal and apocalyptic war; of what drew them to the battlefields of Iraq and Syria; and of what has kept many of them there as Europe and the west have scrambled to stem the flow, first of their own nationals fleeing to join Isis and now of millions of refugees fleeing the other way.

It is told largely by five men with whom I have spoken, at some length, over the past four years, inside Syria and Iraq. Their motivations are similar, but in some cases they are diverse and contradictory. All of them draw at least some inspiration from the prophecy of an epochal confrontation in Dabiq; they see themselves as underdogs, fired by a sense of divine mission. Individually, each man painted a distinct portrait of his reasons for joining a movement that is fast causing the collapse of an order that has bound the region together for centuries, and posing a direct challenge to all the Middle East's current forms of governance, threatening autocracies, monarchies and quasi-democracies alike.

All of these men believed that by travelling to fight for the caliphate, they were standard-bearers of their faith. They also felt sure they were acting to restore Islam to its lost glories - and had a sense of privilege and pride that their generation was the one that had been chosen to right the wrongs of the past. These sentiments are shared by many others I have met: two senior Isis members who have been captured by Iraqi forces and are now facing death sentences; a Syria-based Tunisian fighter who believes his duty is to obey the orders of his superiors with unswerving servility; and even one former member of a mainstream rebel militia, who joined the ranks of his jihadi foes when he realised the battle was turning in their favour.

But they also had myriad other reasons for joining the terror group that had little to do with their understanding of Islamic scripture or any sense of holy war. Some saw themselves as victims of oppression, others as sons of dispossessed families. Another thought of himself as a cultural warrior, not a holy warrior: he argued that joining the jihad was an entirely practical obligation, necessary to restore the caliphate and bring on the prophecy of the end times.

Few were untouched by a yearning for the collective memory of the early centuries of Islam, alongside contemporary grievances about a humiliating loss of power at the hands of the west in recent years. By late 2014, they were all fighting under the banner of the most radical and dangerous jihadi group to have formed in the past 30 years. And Dabiq was now ground zero for their struggle. [...]

Abu Ahmed, with whom I remain in regular contact, became more involved with Isis from mid-2013. He remains disaffected with the group, which he believes has strayed well beyond its original remit of fighting the US army and defending Sunnis against their marginalisation in post-Saddam Iraq. But even with his reluctance, he still believes that he too is helping to restore lost glories - of both ancient Islamic civilisation and a more recent era of Sunni power - by fighting against Iran and the Assad regime. "This is just a reality," he said. "The Americans are working with Iran against the Sunnis. This is not a conspiracy theory."

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