They are the Ninewa Operations Command's commando battalion. Many of the battalion's about 300 soldiers still have family in Mosul. And they want their city back – mosque and all.

"They have one purpose in life and that is to retake Mosul," said Lieutenant-Colonel Jim Hammett, who commands the Australian and New Zealand teams that are training the battalion and other Iraqi forces.

Insofar as the complicated set of conflicts in the Middle East can be broken down into manageable chunks, the looming battle for Mosul represents the keystone for any possible collapse of IS in Iraq.

But it will be a hard fight. As with Ramadi, a much smaller city that Iraqi forces have largely retaken, soldiers such as those from the Ninewa battalion will face an onslaught of truck bombs, booby traps, snipers and surprise night attacks when they try to wrest Iraq's second-largest city from IS.

Australian and Kiwi trainers have their work cut out for them in preparing the battalion. While the Iraqis call themselves commandos, their definition doesn't remotely touch that of Australia or other modern armies. They have been issued new M16 rifles, body armour and helmets, which as one Australian observed will, after their next payday, be festooned with functionless brackets, lasers and telescopes in a bid – common among Iraqi soldiers – to emulate Western special forces.

But they start with two natural strengths – they have motivation and good leadership, neither of which is a given in the Iraqi army.

Elsewhere in the military, politicisation, corruption and rigid hierarchy have hollowed out entire brigades. Sectarianism meanwhile puts limits on the trust the predominantly Shiite army enjoys in Sunni-populated areas such as Mosul – let alone irregular Shiite militias.

But the battalion will be fighting on home soil under a strong commanding officer, a dapper, middle-aged man with a fastidious appearance and a proclivity to speak lyrically. [To avoid reprisals against families in Mosul, Australian reporters have agreed not to name soldiers from the battalion.]

"He's quite a charismatic chap, probably not quite the typical commanding officer we've encountered thus far," Colonel Gavin Keating, the commander of the Australian and New Zealand training forces of Task Group Taji, said.

"He takes an active interest in their training. He's much more actively involved than most of the other commanding officers that we've encountered. He regularly addresses the soldiers and seems to know them quite well."

For his part, the Iraqi officer vows that he will plant the Australian and Kiwi flags alongside Iraq's when he and his men help liberate their city from IS, whose fighters in Mosul number anywhere from about 2000 to 10,000, according to varying estimates.

"The city where we were born means a lot to us. That's where we grew up, that's where we were raised," the officer said. "So we need to do anything to liberate it. We have friends, we have brothers ... All the families and all the friends will go back to the homes they're used to."

He said his men respect and love him because they know he will be there behind them when they go into combat. A critical reason why Iraqi forces broke in the face of IS advance in 2014 was that many officers were the first to run.

One of the battalion's warrant officers is a big man, 1.93 metres and with a sturdy build. His farm is now part of IS's "caliphate". On a chilly evening this week waiting for a night exercise, he was enforcing discipline like a man who has been pushed off his land and is determined to get it back.

Many soldiers of the NOC battalion said they had family members still in the city. A 27-year-old sergeant major said his father was there. He hasn't spoken to him in six months.

"I don't know much about him because the communications are shut down in Mosul. I just know he is still alive," he said. "[My father] said the situation was bad and getting worse since Daesh [IS] took control. The morale of the citizens is bad because the grocery stores are shutting down because of how IS has treated the civilians.

"I can't wait to go there and beat IS."

However bold their rhetoric, the fight will be long and bloody. While individual soldiers were vague about how they left Mosul in the first place, it is likely many of them were members of units routed when militants swept into the city in a lighting offensive in 2014.

The commanding officer, however, said his troops had received a major confidence boost from the Anzac training.

Colonel Keating said of the commanding officer: "He's a pretty seasoned campaigner. He knows that Mosul's going to be a pretty hard nut to crack."

Unlike Ramadi, which was fought largely by elite Iraqi special forces, regular troops such as the Ninewa battalion will "100 per cent" be heavily involved in the fight for Mosul simply because it will be far too big for the special forces alone, Colonel Steve Warren, spokesman for the coalition's operations against IS, said.

IS, whose commanders include former officers from Saddam Hussein's army, has long been seen as a serious conventional military foe rather than just a terrorist insurgency. Colonel Warren, speaking to Australian reporters this week, described it as "a hybrid-conventional war rather than a terrorist insurgency".

That is why the Taji Task Group put the NOC battalion through exercises in clearing buildings by night and advancing on an enemy over open terrain in a formation of four men. These are basic conventional military skills.

"We are fairly certain they will be fighting in an urban environment, they will be attacked at night and they will experience surprise attacks and they will suffer casualties," Colonel Hammett said. "So we do our best to prepare them for that."

The Pentagon's stated plan is for the Iraqi army to move into Mosul from the south while the potent Kurdish forces squeeze the militants from the north.

The Ninewa battalion has some Kurdish and even a couple of Shiite members. But as a local, predominantly Sunni force it could be critical in maintaining control of the largely Sunni city if and when IS is driven out. In contrast, Shiite forces would probably foment a backlash among residents.

"Our first priority is holding the ground so that no militias can take control of the city," one soldier said. "It will be difficult but Mosul's people will help us do the job."

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