You hear a familiar form of anger in some of the interviews with people leaving the so-called Islamic State.

There's regret about the bloody impact of the final bombardment - the way the caliphate ended - but what’s often absent is any rejection of the ideals upon which Isis was built.

"The people don’t have food… They’re tired, morale is low I suppose", one woman who claimed to be British told ITV News as she left the final patch of Isis territory earlier this month.

But when asked whether the end of the caliphate amounted to the end of the terror group itself, she sanguinely responded: "Not over. Not over yet".

She was correct - territorial defeat would have been fatal for a territorial organisation, but Isis is much more than that.

U.S.-backed Syrian Democratic Forces (SDF) fighters celebrate their territorial gains over Islamic State militants in Baghouz, Syria. Credit: AP

Perhaps we shouldn’t be surprised former fighters and families are not immediately and publicly repentant.

But clearly, Isis has not been defeated given the enduring appeal of its ideology.

Claims of "mission accomplished" are exposed as premature by the continuing and widespread support for the group’s core principles, even by many of those who have rejected aspects of its reality.

Isis is already evolving, consolidating and regrouping.

It has a following and a future.

Isis 2.0 might not include a central military command, but by shifting to "asymmetric warfare" it would simply be reverting to a more conventional model for terrorist organisations.

The group remains active; it is thought to still have access to revenue through criminal activities, and it continues to attract some foreign fighters to Syria and Iraq.

There are growing numbers of Isis-affiliated militants in Afghanistan, Libya and South-East Asia - creating new opportunities to ignite insurgencies around the world.

No other organisation has done what Isis did.

Smoke rises from a strike on Baghouz, Syria, on the Islamic State group's last piece of territory. Credit: AP

Before it, Al-Qaeda brought down the Twin Towers and changed history, but it never matched the grotesque achievements of the creation of a "caliphate" - a bloody hellscape that stretched across an area the size of Great Britain and from where several hundred terrorist attacks killing several thousand people around the world were inspired or directed.

And yet its greatest success was not the war it fought with AK-47s, but the one waged with propaganda videos and a brutal sectarian narrative.

Its most fertile battlefield was in the minds of young people who were so enticed by its grim utopia that they crossed countries and continents to live and to fight there.

This was an organisation that attracted recruits from almost every major town and city in Britain - despite, and in many cases because of the violence, the enslavement, the subjugation, the kidnappings, the torture, the beheadings, the execution of hostages, the slaughter in public squares and the grooming of children as fighters.

Syrian Democratic Forces (SDF) head out on an operation in Baghouz. Credit: AP

Some set off in search of a macho hierarchy, or were drawn in by the apparent simplicity of a new society.

Some claim to have left their home countries because they felt marginalised within the societies that raised them, others were seeking adventure and many more were simply brutal psychopaths.

Battering the weapons stores and logistics facilities of the Islamic State won’t have been enough to end the complex appeal of a perverse ideology which seemed irresistible to so many, and which continues to be misunderstood by many western governments.

President Donald Trump was wrong to have boasted "we have won against ISIS" in a video posted on his Twitter account in December.

For a less delusional assessment, consider the Pentagon’s analysis released last month, which concluded Isis could re-emerge in Syria within six to 12 months without "continued counterterrorism pressure" and is already "regenerating key functions and capabilities" in Iraq.

That assessment did not persuade the White House to halt the withdrawal of US troops from Syria - a decision which many analysts believe will sew the seeds of future chaos.

The foundation of Isis were laid a decade before the creation of a "caliphate" was declared in 2014.

This has been a long war, and it is not yet over.