Chemical weapons are said to "make deliberate use of the toxic properties of chemical substances to inflict death". At the start of World War II it was widely reported in newspapers that "entire regions of Europe" would be turned into "lifeless wastelands". However, chemical weapons were not used to the extent predicted by the press.
An unintended chemical weapon release occurred at the port of Bari. A German attack on the evening of December 2, 1943, damaged U.S. vessels in the harbour and the resultant release from their hulls of mustard gas inflicted a total of 628 casualties.
The U.S. Government was highly criticized for exposing American service members to chemical agents while testing the effects of exposure. These tests were often performed without the consent or prior knowledge of the soldiers affected. Australian service personnel were also exposed as a result of the "Brook Island trials" carried out by the British Government to determine the likely consequences of chemical warfare in tropical conditions; little was known of such possibilities at that time.
Some chemical agents are designed to produce mind-altering changes; rendering the victim unable to perform their assigned mission. These are classified as incapacitating agents, and lethality is not a factor of their effectiveness.