Iraq’s prime minister, Haider Abadi, says the assault on Mosul is days away. Confidence is high: Iraq’s armed forces have not lost a major battle for 16 months in their war against Islamic State. But rather than flee, IS might make a last stand. Iraq’s second city, where the group’s leader, Abu Bakr Baghdadi, declared his caliphate, is the jihadists’ greatest prize. Fortifications include an oil-filled ditch and heavily mined approach roads; the 1m-plus civilian population are human shields. An intensive bombardment of the city could invite uncomfortable comparisons to Russia’s devastation of Aleppo in next-door Syria. America wants Iraq’s army to take the lead in the 60-state coalition. But a plethora of other forces—such as Iranian-backed Shia militias—are vying to share the glory, and the Kurdish Peshmerga and their Turkish patrons might yet intervene to keep others out. With the forces arrayed against it already bickering, IS’s defeat is far from certain.