China Japanese invasion

There are two points that emerge from these chapters that are worth drawing brief attention to here. First, it is clear that in those rare cases since the First World War when chemical weapons have been used on a substantial scale, it has always been against an enemy known to be deficient in anti-gas protective equipment or retaliatory capability. Second, in all substantiated cases of chemical warfare during the twentieth century, the employment of chemical irritants, such as tear gas, has always preceded the resort to more lethal chemical agents. This is true for the First World War, the Italian invasion of Ethiopia, the Japanese invasion of China and the Yemeni Civil War. In Vietnam, where irritants were used on a scale approaching that of the First World War, the reports of uses of more lethal chemicals remain unsubstantiated. These points seem to... 

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