There, on March 16, 1988, Saddam Hussein attacked Kurdish villagers with deadly nerve gas, killing as many as five thousand men, women, and children in history’s worst chemical attack against a civilian population. The region never fully recovered; after the first Iraq war, in 1991, daily patrols by U.S. aircraft kept Saddam’s planes and tanks out of Kurdish settlements, but the absence of a central authority gave rise to local militias and warlords that skirmished with Iraqi ground troops and with each other.