(CNN) A familiar pattern is emerging as Iraqi forces begin the final phase of their offensive to clear ISIS fighters from western Mosul. They edge towards the city limits, using artillery and airstrikes to soften up the terror group's defenses. ISIS retaliates with suicide bombs, exploits its tunnel networks and activates sleeper cells elsewhere in the city. A long battle of attrition is underway, with some 750,000 civilians caught in the middle. For the Iraqi army and government, the prize is clearing ISIS from the last city it holds in Iraq. What does the battle look like? The battle for western Mosul is likely to be tougher than that for the eastern half of the city, which took well over two months. Satellite imagery and witness accounts indicate that ISIS' defenses are thicker here, and the warren of alleys in the old city is impenetrable to armored vehicles.The effort to take western Mosul back from ISIS will be a battle of attritionCivilians trapped by the fighting have no easy escape route
A CNN team in eastern _ last month found the brittle mood among a civilian population that was beginning to return home but wary of the fragile security situation.