ISIS forces prepare to flee as Iraqi soldiers enter stronghold of Tikrit . Iraqi forces close in on city centre that has been controlled by ISIS since 2003 . makes ISIS stronghold vital if forces are to force ISIS out of Mosul . Mosul is the terror group 's Iraqi power base and is 140 miles north of Tikrit .
ISIS stealing cars to flee as Iraqi soldiers enter stronghold of Tikrit . Iraqi forces closing in on city centre that has been held by ISIS since June . Retaking ISIS stronghold vital if forces are to force ISIS out of Mosul . Mosul is the terror group 's Iraqi power base and is 140 miles north of Tikrit .