Max Becherer/Polaris, for The New York Times A cemetery in Sewsenan, a Kurdish village in northern Iraq, holds the remains of nearly 70 people killed in a chemical attack by Saddam Hussein’s military forces on March 22, 1988. SEWSENAN, Iraq, Aug. 18 — When death came to this village, it had a sweet smell, like perfume. “People wanted to inhale it,” Robitan Hama Amin said. So went Mr. Amin’s memory of the first encounter between the Kurds of this mountain redoubt and Saddam Hussein’s chemical weapons. The attack came at dinnertime on March 22, 1988. Mr. Amin had just...