7h 55min, apr 22, 1915 y - Invention of chemical warfar

Description:

Chemical warfare is a type of warfare that include toxic chemicals and gas. It was used to weaken the battle field before a battle.

1.https://owlcation.com/humanities/The-Gruesome-Military-Tactics-of-World-War-I

2.https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRUBYPHnHaSBocR2-EXi5j31Z8x2UpV1E9_u0QnMiRKuwv88jX9

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