What type of agents hold historical significance as forerunners of chemical warfare?

Pulmonary agents hold historical significance in the context of chemical warfare, particularly due to their early use in World War I. These agents are designed to damage the respiratory system, leading to severe pulmonary complications and potentially death upon inhalation. Notable examples include phosgene and chlorine gas, which were among the first chemical agents used on the battlefield. The impact of these agents in combat not only caused immediate physical harm but also instilled fear and panic among troops, marking a significant shift in the nature of warfare.

While other types of chemical agents such as nerve agents, cytotoxic agents, and blister agents play critical roles in chemical warfare, the early historical significance and widespread use of pulmonary agents during key conflicts solidify their status as forerunners in this field. Thus, the relevance of pulmonary agents as foundational to the development of chemical warfare is well-established.