The first full-scale deployment of deadly chemical warfare agents during World War I was at the Second Battle of Ypres, on April 22, 1915, when the Germans attacked French, Canadian and Algerian troops with chlorine gas. Deaths were light, though casualties relatively heavy.

Bio warfare is living creatures; if a contaminated mosquito was delivered to the enemy that would be bio warfare. Chemical warfare is just what it says: chemicals.

trench warfare chemical warfare

The definition of the term 'chemical warfare' is warfare where one side uses chemical weapons to kill or injure those on the other sides. It is a controversial weapon and condemned by the UN.

Warfare using mustard gas and chlorine gas.