To find Mosul's cops, you drive to a gray dot of a village in an endless desert. The village, Mahana, was retaken from the Islamic State a few months ago and for now it's the police base for cops who left Mosul when ISIS took over more than two years ago.

Iraq's army and its allies are now battling their way through rural areas toward the larger prize of retaking Mosul. Helicopters buzz back and forth from the frontlines. Every breath is bitter with smoke from oil wells set alight by ISIS.

Inside the police base, the mood is upbeat. The police are helping the army with logistics. Presiding over a bank of radios and several battlefield maps is police Gen. Abdulkareem al-Jubouri.

"Yesterday, they liberated my village," he says of the tiny hamlet where his mother and sisters lived for more than two years under ISIS rule.

"I feel great happiness today," he says. "First, because we liberate our areas and our people from ISIS, everyone is happy, not just me. The officers, the recruits, everyone is happy. Today I went to my parents — such a great happiness."

He went with the army and several of his men on a mission to figure out how to hold the village. But he did have time to hug his mother

"She was crying," he said.

Gen. Jubouri is optimistic. He believes the police, with their knowledge of the area, should be the holding force when and if ISIS is expelled from Mosul.

But the Mosul police have a reputation to overcome. Before ISIS took Mosul in June 2014, people in the city complained that the police were corrupt and infiltrated by al-Qaida.

The police chief, Gen. Wathiq al-Hamdani, is pretty blunt.

"Some of them, they have a relationship with the terrorists, and some of the police who stayed in Mosul now, they work with ISIS," he says.

He says this refers to about 20 percent of the force. But now, he says, the police have had training from the U.S.-led coalition outside Mosul, and they're ready to go back and help rebuild the place.

But even if the police at the training base aren't allied with the extremists, there could still be problems like discipline and a desire for revenge. For many police, the battle against ISIS is personal. They lost friends and family, and their desire to settle scores could override their training.

A young police corporal, Muhannad Ahmed, is also from the village now retaken from ISIS, and says his relatives there are like people who died and were given life again. He talks about what he'll do in he encounters anyone linked to ISIS.

"I'm going to go and slaughter them all," he says. "I won't leave anyone in their family. I will erase them from the face of the earth. The brother or father of anyone who is with ISIS."

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