Using chemical weapons has long been regarded as overstepping the boundary of acceptable warfare. As early as 1675, France and Germany agreed in Strasbourg to ban poisoned bullets. Large-scale chemical warfare began on 22 April 1915, when German forces released chlorine gas near Ypres in Belgium, the world’s first use of a weapon of mass destruction. Decades of international efforts to ban such acts culminated in the Chemical Weapons Convention, which entered into force on 29 April 199Large-scale chemical warfare began on April 22, 1915, when German forces released chlorine gas near Ypres in Belgium, the world’s first use of a weapon of mass destruction. Decades of international efforts to ban such acts culminated in the Chemical Weapons Convention, which entered into force on April 29, 1997. From the First World War to Vietnam, the Iraqi city of Halabja to Syria and Russia, the following images document more than a century of chemical warfare and its human cost and are a reminder ...