- Video report by ITV News Correspondent Richard Pallot
US-backed Syrian forces say they have liberated the last area held by the Islamic State group in the eastern Syrian village of Baghouz, declaring victory over the extremists and the end of their self-declared caliphate.
Mustafa Bali, a spokesman for the Syrian Democratic Forces, said on Twitter that "Baghouz is free and the military victory against Daesh has been achieved", referring to the group by its Arabic acronym.
Bali said the so-called caliphate, which once sprawled across much of Syria and neighbouring Iraq, is gone, and pledged to continue the fight against remnants of the extremist group until they are completely eradicated.
The announcement marks the end of a four-and-a-half year campaign by an array of forces against the extremist group, which at its height in 2014 ruled an area the size of the United Kingdom, including several major cities and towns, and around eight million people.
Prime Minister Theresa May credited the "immense courage" of the UK armed forces and their allies, while Foreign Secretary Jeremy Hunt vowed Britain will "remain resolute" in its commitment against the group, also known as Daesh, and its "poisonous ideology".
Prime Minister Theresa May has commented on the SDF's victory saying: "The liberation of the last Daesh-held territory wouldn't have been possible without the immense courage of UK military and our allies.
"We will continue to do what is necessary to protect the British people, our Allies and partners from the threat Daesh poses."
Foreign Secretary Jeremy Hunt has also responded on social media as he tweeted: "Today's liberation of Daesh's last territory in Syria is a historic achievement.
"But the fight is NOT over.
"We remain resolute in our commitment to tackle the real threat Daesh and its poisonous ideology poses to people in Iraq, Syria and around the world."
The group no longer controls any territory in Syria or Iraq, but continues to carry out insurgent attacks in both countries.
It also maintains affiliates in Egypt’s Sinai Peninsula, Afghanistan and elsewhere.
British forces will not scale-back their presence in Syria and Iraq following the capture of the last remaining territory.
Major General Chris Ghika, Deputy Commander of the Global Coalition's joint task force, said the terror organisation is by no means "leaderless or rudderless", despite its loss of physical territory.
But he said he could not predict whether the fall of the physical territory would substantially increase or decrease the terror risk to the UK.
- ITV News International Affairs Editor Rageh Omaar on the rise and fall of so-called Islamic State
- Timeline: Islamic State’s rise, rampage and fall
Here is a timeline covering the rise of the murderous group, key events during its rampage of terror and the eventual demise.
In the wake of the US-led invasion of Iraq, Jordanian militant Abu Musab al Zarqawi establishes al Qaida in Iraq.
He is linked to countless attacks and killings - including the videotaped executions of Western hostages Nick Berg and Ken Bigley.
Al Zarqawi is killed following an American air strike in Iraq.
Months after his death the name of the group is changed to Islamic State in Iraq.
Abu Bakr al Baghdadi takes the reins of the Sunni extremist group.
Al Baghdadi renames Islamic State in Iraq, the Islamic State in Iraq and the Levant, or Isil.
- 2014 - January to June
The group blitzes across vast swathes of Syria and Iraq.
In January, the Iraqi city of Fallujah falls into the hands of its fighters, followed by the Syrian city of Raqqa.
Isil then begins its spread into north and western Iraq with brutal efficiency, capturing Mosul and Tikrit and even advancing to the edges of Baghdad, the Iraqi capital.
In June, at the Great Mosque of al-Nuri in Mosul – with its leaning minaret – al Baghdadi declares the establishment of a new Islamic State or caliphate – renaming itself as such.
- 2014 - June to September
August features the barbaric murder and enslavement of thousands of Yazidi religious minority in northern Iraq - surrounding and trapping many on Mount Sinjar.
The first of many gruesome videos showing the beheading and murder of western hostages begins.
American journalist James Foley is the first - with others in the months following.
In September, the US-led Global Coalition is formed and announces its commitment to eradicating Islamic State in Syria and Iraq.
The bloodthirsty extremist group begins the process of claiming responsibility for a number of atrocities and attacks that are carried out around the world over the coming months and years.
This includes Sousse in June, when 30 Britons are among the 38 tourists killed as gunman Seifeddine Rezgui opens fire on a beach in the Tunisian holiday resort.
In November, this time through suicide bomb and gun attacks at various entertainment hotspots in Paris, more than 130 people are killed and hundreds injured.
Jihadi John, whose real name is Mohammed Emwazi - the knife-wielding killer believed to be responsible for the deaths of Western hostages in a number of choreographed videos - is killed in a drone strike the same month.
Explosions at Zaventem airport and metro station in Brussels kill 32 people in March. Islamic State claims responsibility.
In the summer, the group also claims responsibility for the Bastille Day attack in Nice, France, which leaves more than 80 dead, and the Orlando, Florida, nightclub shooting that kills 49.
This year marks the beginning of a raft of devastating defeats and losses for Islamic State.
By October the group have also lost control of its de-facto capital, Raqqa in Syria. Come December, then-Iraqi prime minister Haider al-Abadi formally announces that Islamic State has been driven out of the country.
The cult remains deadly, claiming a string of fatal attacks in Iraq including one at a Sunni Muslim funeral.
Then its fighters slaughter more than 200 people and injure some 180 more in coordinated suicide bombings and gun attacks in and around Sweida in Syria.
By March the group, which formerly controlled a territory the size of the UK, has been reduced to a sliver of land trapped between the Euphrates River and its former encampment now held by the Syrian Democratic Forces.