On October 17, 18,000 Iraqi Security Forces, 10,000 Kurds, several thousand policemen, and an array of Sunni and Shia militia fighters, along with their American advisors, began a long-awaited campaign to take back the Iraqi city of Mosul from the Islamic State. “I am announcing today the beginning of these heroic operations to liberate you from the brutality and terrorism of ISIS,” Prime Minister Haider al-Abadi declared in a televised statement marking the start of the operation. “God willing, we will meet soon on the ground of Mosul where we will all celebrate the liberation and your freedom.”
Mosul fell to ISIS in June 2014, in a staggering humiliation for the U.S.-financed and -trained Iraqi military. The Islamic State declared itself a caliphate there, and in the months that followed, expanded its territory, at one point coming to occupy large parts of Syria and Iraq and effectively erasing parts of the border between the two. In the meantime, its apocalyptic aspirations helped inspire a new generation of attackers around the world.
From its peak in 2014, ISIS has today lost by one estimate roughly half of the territory it controlled in Iraq and 20 percent in Syria. But the campaign to take back Mosul, once Iraq’s second-largest city and the group’s last major Iraqi stronghold, is destined to be particularly complex. An Iraqi Kurdish general has estimated it could take two months, and the coalition faces numerous potential dangers from, among other things, ethnic and sectarian tensions within their own ranks; improvised explosive devices, booby traps, and possibly chemical weapons; an estimated 3,000 to 5,000 ISIS fighters in the city and possible sleeper cells hiding among the civilian population; and, as the battle accelerates, a surge of up to 1.3 million refugees out of the city.