An Iraqi soldier stands on a military vehicle near the town of Qayyarah, which was recently taken from ISIS in the Iraqi army’s push to Mosul. In the background, smoke billows from oil wells set ablaze by the fleeing militants. (Photo: Safin Hamad/AFP/Getty Images)

ERBIL, Iraq – The Iraqi Army is preparing to close in on the northern city of Mosul, which has been under the fierce occupation of the Islamic State since July 2014.

With a population once thought to reach nearly 2 million people, Mosul is the largest city ISIS holds, and the battle for it will be one of the largest ever against the armed group. Here are some facts to keep in mind as the battle approaches.

Why is Mosul important?

Mosul is rich with oil and famous for its marble. When ISIS captured the city, it took control of its oil refineries.

There have been reports of torture, including burning women from the Yazidi minority, and sexual slavery during the occupation.

The city has also been known for a large population of Assyrian Christians. It occupies a central position in Nineveh province, with great biblical and historical significance.

It is said to be the burial place of the biblical figure Jonah.

Recapturing the city would be a major blow for ISIS’ prestige and influence in Iraq, and it would be a major financial setback.

A fighter holds an ISIS flag in the city of Mosul in 2014. (Photo: Reuters)

How does the Iraqi army plan to take the stronghold from ISIS?

The Iraqi army hopes to take back Mosul before the end of the year. Operations could start as soon as October.

Yahoo News spoke with commanding Gen. Najim al-Jubouri, who is overseeing Mosul operations. He said, “Our battle in Mosul will be different [from other battles], we have a very high level of cooperation and coordination with coalition forces. We’ll begin with the coalition forces, they’ll strike [by air], the enemy, ISIS, and after that, we will move.”

The Iraqi army plans to surround the city from the north and south, leading the charge into Mosul, while being supported by Kurdish fighters, known as the peshmerga, and popular mobilization forces or allied militias.

Slideshow: The battle for Mosul, Iraq >>>

Jubouri said, “We put in good plans, with the coalition forces, and we will cut all roads they [ISIS] will [try to] escape.”

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The general is also encouraging residents to stay in their homes during the fight, in hopes to avoid a mass civilian evacuation. The United Nations is anticipating as many as a million and a half residents could be affected by the battle and will likely attempt to flee.

“We will deal with the battle like good surgery, pull out the cancer, in the villages,” Jubouri said, “In the east side of the [Tigris] river of Makhmur, we had good experience. The people stayed in their homes.”

The Iraqi Army recaptured Makhmur in May. Jubouri said some of people actually rose up and helped the army push ISIS out, in Makhmur and in Qayyara, which was recaptured in recent weeks. He hopes for the same in Mosul.

Iraqis stand near oil wells set ablaze by fleeing ISIS militants. (Photo: Safin Hamad/AFP/Getty Images)

How will the U.S. be involved?

The United States will continue to conduct air strikes against ISIS and will be coordinating with the Iraqi military on logistical operations.

Yahoo News requested a visit to the Qayyara Air Base, where U.S. troops have set up a logistics hub, but the request was denied and logistics officers were not able to respond.

However, the U.S. Army Coalition press office director in Kuwait, Col. Joe Scrocca, told Yahoo News in an email, the “ISF [Iraqi security forces] have grown considerably in experience, capacity and confidence. Our primary role has been to enable our partnered forces through our [air] strike capabilities” and training the Iraqi forces.

The U.S. has insisted it will not participate directly in Mosul ground operations.

But as the battle draws near, the American military presence in the region has increased to some 5,000 troops, and special forces are conducting covert operations behind enemy lines.

“The military fight against [ISIS] is an essential component of the larger strategy to defeat the terrorist group,” Scrocca explained, and the aim of the airstrikes is to apply “a disciplined, systematic targeting method to avoid and minimize civilian casualties.”

What are the humanitarian concerns?

Besides the concern to minimize civilian casualties, commanders worry about ISIS using residents as human shields.

“It’s what we expect, they did that before,” Jubouri said. “But when we are involved with them in the battle, we take care of the people.” The general believes that the army will be able to minimize casualties even if ISIS attempts to use civilians as human shields and that the forces under his command will do what is necessary to save lives. “My troops, under my authority, we always put the human rights in our minds,” he said.

In addition, many camps for Iraq’s internally displaced people are preparing for a large influx from Mosul.

The International Organization of Migration has already recorded over 90,000 displaced people since June.

One of the largest encampments, in Dibaga, just southeast of Mosul, houses more than 36,000 people in a space that has tents for only around 10,000.

Burning oil wells near the Dibaga camp can cause respiratory problems for residents. (Photo: Ash Gallagher for Yahoo News)

Yahoo News visited the camp. Smoke from nearby oil refineries fills the air, and people often cover their mouths to keep from breathing it. The camp’s children roam in big groups, and candy and snack stations are on the outer edges. Doctors outside the camp’s hospital have a small tent set up to give measles and polio vaccines to children.

A few air-conditioned rooms make up the camp’s offices, next to the hospital. The camp manager, Rzqar Abed, spoke with Yahoo News. He said that “not having enough space for everyone is a real dilemma.” He said many people were crowding together in their tents: “These people are tribal, they’re used to living with each other, and there are families right now who do not have a [tent] who are living with their relatives.”

For the remaining people on the streets, organizations are struggling to get more tents up with basic supplies like blankets, mattresses, fans and food.

Security within the camp is also a concern. At the entrance to Dibaga, there is a screening section in which new arrivals, particularly men and boys, are questioned about possible links to ISIS before being allowed in. But human rights groups accused community and religious leaders of attempting to recruit teenagers to fight with the militias.

Abed said they are trying to discourage the behavior, but it is often difficult to control.

Dibaga camp does expect new internally displaced persons as the battle for Mosul approaches. Abed said, “If the people feel safer and they are sure the mortars from ISIS will not get to them, they will stay [in their homes],” but he is still preparing for at least 800,000 to flee. Many of those are likely to end up in Dibaga.

A displaced Iraqi family gathers in their tent after cooking doulma on a hot summer day in Dibaga camp, where they have been for several months. (Photo: Ash Gallagher for Yahoo News)

What will happen once ISIS is defeated in Mosul?

The coalition of nations working in Iraq has committed $2 billion to humanitarian groups for rebuilding Mosul, including physical infrastructure and public services.

Scrocca said the “reconstruction efforts [will] follow closely on the heels of progress in the military campaign. Long-term success is tied to the Iraqi government’s ability to make strides toward reform and more inclusiveness.”

Since ISIS has ruled Mosul for so long, the question of who will govern afterward remains unanswered. The Kurdish government and peshmerga forces hope to negotiate with the Iraqi government to gain a primary role. But minorities in the city have called for an independent province and governing administration.

Meanwhile, the Iraqi Parliament is scrambling to approve a candidate to replace the country’s recently dismissed defense minister, but in order to meet its year-end goal, the Iraqi army is expected to move toward the center of Mosul in the coming weeks. If the Iraqi army can sack ISIS successfully, it could help restore its reputation as a fighting force against terrorism in the region.