
Thousands of troops are massing outside Isis-held Mosul in preparation for a battle that could spell the end of the terror group in Iraq.

The fight to reclaim the city is expected to begin next week in what will be the biggest Iraqi military operation since the US-led invasion in 2003.

A successful conquest would destroy ISIS's last bastion of power in the country, and represent a serious blow to its legitimacy.

Some 30,000 Iraqi troops are expected to take part in the battle, with support from US special forces and western coalition warplanes.

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Thousands of troops are massing outside Isis-held Mosul in preparation for a battle that could spell the end of the terror group in Iraq. Pictured is a brigade of Peshmerga fighters

The fight to reclaim the city, Iraq's second largest, is expected to begin next week in what will be the country's biggest military operation since the US-led invasion in 2003. Pictured is a mortar team setting up a barrel outside Mosul

A successful conquest, which is being spearheaded by Iraqi government forces,(pictured) would destroy Islamic State's last bastion of power in the country, and represent a serious blow to its legitimacy

The Iraqi army recaptured the town of Qayyarah in August, and is advancing 25 miles to Mosul in preparation for the new offensive.

'All the troops are ready, now they are just waiting for the order from the prime minister,' said Major General Najim al-Jobori, one of the top Iraqi commanders overseeing the Mosul operation.

'The head of the snake is Mosul,' he said. 'I think ISIS knows this is the end of ISIS in Iraq.'

Situated on the west bank of the Tigris River, 250 miles from Baghdad, Mosul is Iraq's second largest city.

It used to be a bustling city of two and a half million people, and was famed for its university, one of the largest education centres in the Middle East.

Since Mosul's capture by ISIS in June 2014, it has been the scene of increasing brutal atrocities as the terror group struggles to contain discontent among 600,000 remaining residents.

In August, nine young men were tied to iron poles and cut in half with chainsaws after they were accused of belonging to a 'resistance faction'.

'Isil is panicked,' one resident told The Telegraph.

'Since they lost Qayyarah, they have begun to tighten their security; carrying out mass arrests and raiding houses in search for weapons and illegal phones.'

A child waves as a Pershmerga military convoy travels towards Mosul. Situated on the west bank of the Tigris River, 250 miles from Baghdad, the city used to house two and a half million people

Mosul was famed for its university,one of the largest education centres in the Middle East. Its recapture would destroy Islamic State's last bastion of power in Iraq

Peshmerga forces stand guard at the Basika front as US artillery units bomb the Deash positions in the east of Mosul with a howitzer

ISIS commanders realise the symbolic importance of maintaining its territory in Iraq. Pictured are Iraqi security forces

Mosul is by far the biggest city held by the militants - around four to five times the size of any other urban area recaptured so far from the fighters

Iraq was where the group's founder, Abu Bakr al-Baghdadi, first announced the creation of a 'caliphate' in April 2013

ISIS commanders realise the symbolic importance of maintaining its territory in Iraq.

Mosul is by far the biggest city held by the militants - around four to five times the size of any other urban area recaptured so far from the fighters

Iraq was where the group's founder, Abu Bakr al-Baghdadi, first announced the creation of a 'caliphate' in April 2013.

HOW THE CONQUEST OF MOSUL COULD COST THE UN $1 BILLION Lise Grande, the UN Humanitarian Coordinator for Iraq, said: 'The worst case scenario in Mosul would look something like this: you would have mass expulsion of hundreds of thousands of people. 'You would have hundreds of thousands of people who are held as human shields. 'You would have a chemical attack that would put tens of thousands, hundreds of thousands or maybe even more at grave risk. 'If all that were to happen at the same time it would be catastrophic.' Advertisement

The estimated 60,000 jihadis in the city have dug in for what is expected to be a complex and bloody battle.

A 7ft-by-7ft trench has been dug around Mosul's perimeter, alongside numerous barriers dubbed 'Caliphate fences'.

According to The Telegraph, the jihadis have rigged a chemical plant with explosives with the intention of using the civilian population as human shields.

Despite the formidable defences, the UN estimates more than half a million people have already managed to flee the oncoming offensive.

The capture of the city could spark the world's most complex humanitarian crisis, with one million people expected to be displaced from the city and its surrounding areas.

ISIS fighters are expected to fight hard and have a history of forcing civilians to stay in harm's way during previous battles to defend territory.

There are also fears that the liberation of the city by the Iraqi army, which relies heavily on Shia militias, could alienate Mosul's majority Sunni population.

Some Sunnis initially welcomed Islamic State's conquest of the city, and their frustration at being invaded by the rival sect could spark sectarian tensions.

Also helping in the conquest will be the Kurdish Peshmerga, who are aiming to acquire more territory and made it part of Kurdistan.

Also helping in the conquest will be the Kurdish Peshmerga, (pictured) who are aiming to acquire more territory and made it part of Kurdistan

This would be resisted by the Iraqi government, which wants to reassert its control over one of its largest population centres. Pictured are Pershmerga forces preparing their weapons

Soldiers ride on a truck carrying the flag of Kurdistan. Forces have been pouring into the region for days in preparation for the attack, expected next week

Iraq government's anti-terror teams, armoured vehicles and artillery line up in preparation for the offensive against Mosul, which is expected to be bitterly resisted by Isis fighters

Another complication is the presence of Turkish forces in a nearby camp. President Taipei Erdogan said the soldiers were an insurance against attacks on Turkey and wants them to be involved in the assault. Pictured are Iraqi and Peshmerga forces

But Iraq's Prime Minister Haider al-Abadi says Turkish troops have deployed in Iraq without the authorisation of the government. Pictured are Pershmerga forces gathering on the outskirts of Mosul

This would be resisted by the Iraqi government, which wants to reassert its control over one of its largest population centres.

Another complication is the presence of Turkish forces in a nearby camp.

President Taipei Erdogan said the soldiers were an insurance against attacks on Turkey and wants them to be involved in the assault.

He said: 'Nobody should talk about our Bashiqa base. We will stay there. Bashiqa is our insurance against any kind of terrorist activities in Turkey.'

But Iraq's Prime Minister Haider al-Abadi says Turkish troops have deployed in Iraq without the authorisation of the government.