The concept of war could be pretty weird and ironic at times. After all, the purpose of creating all these lethal weapons and engaging in war with the enemies was to cause havoc and suffering to them, right? That could be true in ancient times, but we are not barbaric. So, even when we are killing one another, there are certain rules that had to be adhered to, one of which was the ban on using weapons that caused unnecessary pain and suffering from the enemies. Here are those:
In 1675, the Strasbourg Agreement between France and the Holy Roman Empire was created and signed in response to the increased use of poisoned bullets. The particular poisoned bullets banned in the agreement was the one developed by Leonardo da Vinci that had powdered arsenic and powdered sulfur packed into shells.
According to it, the French nor Holy Roman Empire were not to use poisoned bullets in conflict, making it the very first agreement to ban a weapon of war in modern history.
Before the 1993 Convention on the Prohibition of Chemical Weapons, chemical weapons saw uses during World War I, with both sides developing and using their own poisonous gases. These chemical weapons were usually put into munitions like grenades and artillery shells and then bombarded enemy positions. Among the most famous chemical weapons used with different effects were chlorine gas, mustard gas, and phosgene gas.