Geography: What is considered modern day Mosul is actually the twin cities of Mosul and the ancient Assyrian city of Nineveh, sitting on opposite sides of the Tigris River on the Nineveh Plains in Nineveh province, northern Iraq. It is 400 kilometres north of Baghdad, 85 kilometres west of Erbil, and 125 kilometres south of the border with Turkey. 
 
Demography: The pre-ISIS population of Iraq’s second-largest city was approximately 3 million. Current estimates of the number of people still living in the city vary from 700,000 to over one million.

Mosul’s history of numerous occupations and its situation on a crossroads between cultures means it has a diverse population including Arabs, Turkmen, Christians and Kurds, including Yezidi and Shabak. Historically it also had a sizeable Jewish population.

The majority of the population is Sunni Muslim.
 
Economy: Historically, Mosul was a centre of trade, a thriving city on the Silk Road. It became known for metalwork, a miniature painting style, marble, crude oil and textile production;  muslin gets its name from Mosul. 

Before the ISIS occupation in June 2014, Mosul remained a centre for trade. There is also some oil in Nineveh Province, extracted at the Hain Zala and Batma oil fields before the ISIS takeover.  

The Mosul Dam is one of the largest in the Middle East. 

The city also had gained a reputation as a centre for education. The University of Mosul, established in 1967, rose to become one of the largest education and research centres in the Middle East. The university campus was reportedly adapted into a base for ISIS militants and subsequently bombed by the coalition.
 
History: Mosul was a meeting place of culture and commerce for millennia, creating a city rich in history and diverse in population. A centre of trade between Persia and the Mediterranean, it saw many cultures crossing its streets, often for trade. Others came to conquer the city, including Sumerians, Assyrians, Alexander the Great, Persians, the Ottoman Empire and ISIS.

The geographic area has been inhabited since around 6000 BC. Nineveh, on the east bank of the Tigris, was chosen as the capital of the Assyrian Empire around 700 BC and was briefly the largest city in the world. Mosul, on the west bank, became the principle city in northern Mesopotamia in the 8th century. In 1258 it was sacked by the Mongols. It was part of the Ottoman Empire from 1534 to 1918.

After the First World War, Mosul was brought under temporary British administration. Ottoman Turkey and Allied nations signed the Treaty of Sevres in 1920 that gave Kurds the right to form a state, including those from Mosul.

But the Treaty of Lausanne replaced the Treaty of Sevres in 1923, leaving the fate of Mosul in the hands of the League of Nations. The current Iraq-Turkey border was defined in 1926 under the Frontier Treaty, which saw Turkey give up Mosul on the agreement that Baghdad give Ankara a 10 percent royalty on the city’s oil deposits for 25 years.

Mosul is one of the several “disputed areas” that Erbil and Baghdad vie for control over. As a disputed area, Mosul was included in the no-fly zone imposed over Kurdish areas in 1991.

Mosul under the Caliphate: Mosul fell to the Islamic State on June 10, 2014.
 
It was here that ISIS leader Abu Bakr al-Baghdadi gave a sermon at Mosul’s Great Mosque in the old city, publicly declaring the Caliphate of the Islamic State on July 4, 2014.
 
The largely Sunni population of Mosul, aggrieved by the Shia government in Baghdad, at first welcomed ISIS as liberators, before the Caliphate’s true colours became known.
 
Under ISIS, there have been daily executions, usually held after prayers. Islamic police are everywhere.
  
Residents have no work and no money. Malnutrition is a problem. Supplies are irregular and when they are available, people do not always have money. ISIS demands a tax. If you cannot pay, the militants may seize your home or car.

The people of Mosul say they are “prisoners in a very huge prison.”

Military preparations: The military offensive for Mosul is compelling diverse forces, who are oftentimes at each others’ throats, to work together - Sunni, Shia, Kurd, Arab, Christian, Yezidi, Turkmen, American - though not without problems.
 
The primary force leading the offensive will be the Iraqi army along with Iraqi security forces, including counter-terrorism and police forces. They will be the sole forces entering the city of Mosul. This was decided in discussions between Baghdad, Erbil and coalition partners. Fears of sectarian violence, as seen in Fallujah where Shiite militias, the Hashd al-Shaabi, were accused of serious human rights violations against the Sunni residents, are high and the decision to limit the forces entering the city was made to mitigate that threat.
 
The Iraqi army will be supported by several other forces who will assist in encircling the city. This includes the Kurdish Peshmerga, who are located east and north of Mosul, along with local militia groups trained and operating under Peshmerga command such as Christian and Yezidi brigades. Local Sunni forces, the Hashd al-Watani, trained by Turkey will fight under Peshmerga command. 

The Peshmerga currently control the majority of routes into Mosul; they are also the forces closest to the city, within just a few kilometres.

No force that is not under the command of the Iraqi government will participate.
 
The US-led coalition will play an advisory role in addition to providing air and logistical support.
 
Peshmerga and Iraqi forces have established joint centres to coordinate for the offensive. They have created joint command centres - one located in Erbil and one in Makhmour. Iraqi, Peshmerga, and coalition military leaders operate jointly out of these command centres.
 
They have also created a joint media centre that will operate through three media offices - one from the Peshmerga, one from the Iraqi forces, and one from the international coalition.  A joint media committee will manage the forces’ messages throughout the offensive, publishing statements on the battle for Mosul and Nineveh Province.
 
The Kurdistan Regional Government has given permission to the Iraqi army to enter Kurdish territory in order to approach Mosul.

A 30,000-strong force consisting of Peshmerga, Iraqi security and counter-terrorism forces, local police and 14,000 Nineveh tribal fighters are prepared for the offensive. 

Humanitarian preparations: Up to one million people may flee the military offensive, from the city itself as well as surrounding towns and countryside.
 
The UNHCR is preparing to accept 710,000 people. They have sufficient funds to build three camps for IDPs - with enough space to house 6,300 families in total. They also expect to be able to provide space for IDPs in Daquq near Kirkuk, Salahaddin, Sulaimani, Garmiyan and Debaga camp in Erbil Province. Baghdad is also building three camps with capacity for 20,000 families.
 
It is not enough, however, for the numbers expected. The UNHCR is trying to mitigate that by having emergency shelter kits with basic supplies so IDPs can put up their own tents in open spaces.
 
The UNHCR has appealed for another $16 million to cover emergency supplies and $90 million for winterization - items like blankets, heaters, and kerosene.