Kirkuk: A new Isis attack is the latest challenge for the long-troubled oil-rich city in Iraq

For Kirkuk, its oil-rich surroundings have been more a curse than a blessing.

The northern Iraqi city struck black gold in 1927, while still under the control of the British Empire, and became the country's oil production powerhouse in the north.

At its peak, its oil fields were pumping out 3.2 billion barrels per day, but this has since fallen sharply amid war and mismanagement by the former Iraqi dictator Saddam Hussein, who seized control in 1968.

Kirkuk is in what is now Kurdistan, a semi-autonomous region of Iraq, and was for years a multi-ethnic city.

Many Kurds, who make up the bulk of the 850,000 population, had arrived in Kirkuk in search of work in the city's oil industry. They found oppression by the tyrant Hussein instead.

Hussein wanted to ensure total control over the Kirkuk oil supply and did not want the Kurds, who hated him, to threaten the production that made him, his family and his henchmen rich.

So his Ba'athist government tried to flood Kirkuk with Arabs and force out those of other ethnicities, such as the Assyrians, under its "Arabisation" programme.

According to Human Rights Watch, many of those who were expelled had refused to sign "nationality correction" forms which would have registered them as Arabs and relinquished their actual ethnic identities. Their property and assets were also stolen.

Across Kirkuk and other northern Iraqi cities, hundreds of thousands of Kurds and other non-Arab groups were pushed out by Hussein's oppression.

In the aftermath of the 1991 Gulf War, and at the encouragement of US and British forces, there was a mass uprising against Hussein across Iraq.

The Kurds of Kirkuk rose up. But no armed support came from Western forces and Hussein's Iraqi army crushed them with the help of his helicopter gunships, which he had been allowed to keep despite his invasion of Kuwait which sparked the war he quickly lost.

Days before the uprising, Kurdish men had been rounded up by the government and held in poor conditions, with little food and no toilets, forced to defecate in the corner of their cells.

Many were later released, but some never returned and no explanation was given.

Human rights organisations complained that assessing the plight of the oppressed groups in Kirkuk was difficult because it was one of the only cities in Iraq in which Hussein would not allow a UN office.

There were reports of looting by Iraqi loyalists from the homes and businesses of fleeing Kurds. Some Kurd-owned properties were demolished.

In the battles between Kurdish rebel fighters – called the peshmerga – and the Iraqis, hundreds of civilians were killed in the heavy shelling and crossfire. The Iraqi forces were also accused of committing atrocities.

"When the [Iraqi] tanks entered Kirkuk on March 27, they went to Saddam Hussein Hospital," a local primary school teacher told Human Rights Watch at the time.

"My house is very near the hospital. About 150 meters away from me, I saw troops enter the hospital and then I saw peshmerga being thrown out of the windows.

"After they threw them on the ground, they shot those who were not dead from the fall."

A lab assistant at the hospital gave another grim account.

"Iraqi soldiers opened fire from tanks and helicopters on the hospital," he said.

"When they reached the hospital they entered and went upstairs, where they killed all of the patients, about 30 children, 50 women, and 20 young men.

"I saw them slit the throats of patients with knives and throw some of the patients off the roof or out of windows on the top floor.

"I personally saw five persons thrown out of windows."

Once Hussein's forces had brutalised Kirkuk into submission and re-established control of the city, he continued his policy of Arabisation. Since 1991, it is estimated that 120,000 Kurds and others have been driven out of the city.

When war came back to Iraq in 2003, the Kurds once again seized their moment. This time it came after the fall of Baghdad. Kurdish forces surrounding the city, and residents within it, defeated the Iraqi soldiers trying to defend Hussein's control.

In the messy years after, as Iraq struggled to build a stable democracy and a functioning post-Hussein state, Kurds flooded back to Kirkuk to re-claim land and property that had been stolen from them in the past.

Elections were held and representatives of all of the city's ethnic groups partake in its governance. It now forms part of the self-governing region of Kurdistan, which still falls under the auspices of the Baghdad administration.

The Kurds want to hold an independence referendum in order to establish Kurdistan as a state in its own right, with Kirkuk potentially as its capital.

Since 2005, Kirkuk has become the target of bomb attacks by Iraqi insurgents. In another attack in 2013, 38 people were killed and many more injured as a bomb exploded in a Kirkuk café during Ramadan.

Now Kirkuk and its oil supply face a new threat: the Islamic State, also known as Isis.

Since its birth from the rubble of war-torn Syria next door, the Islamic State – a self-declared caliphate run by violent Islamic extremists – has taken advantage of the post-2003 chaos in Iraq and seized control of territory in the country's north.

It has attacked Kirkuk with bombings and shootings a number of times as it eyes the city's oil wealth. Islamic State has sought to weaken Kirkuk by sabotaging its oil production by attacking nearby infrastructure, causing the level of barrels coming out of the ground to collapse by 90%.

When the advances of the Islamic State threatened Kirkuk in June 2014, after they had taken the second largest city Mosul and other parts of the surrounding area, the Iraqi government forces protecting the city fled.

The peshmerga once again took control of Kirkuk to fill the vacuum left by Iraqi troops. Soon enough, they were pumping oil. Now the city's residents face their latest crisis.

Islamic State fighters have launched a fresh offensive against the city in order to expand their caliphate and seize control of the oil production.

They have so far captured land and villages to the south-west of the city, killing several peshmerga including a senior officer, by taking advantage of a dense fog engulfing the area to attack Kurdish positions overnight.

A suicide attack in the city centre reportedly killed peshmerga general Shirko Rauf, brigade commander of the Kurdish forces in Kirkuk.

Once again, Kirkuk finds itself at war because of the oil it's cursed with.