The French were the first to implement gas into warfare by using tear gas grenades in August of 1914, the first month of WWI.
Tear gas side effects can result in pain with one's vision, respiratory system, and skin. Vomiting and blindness can ensue if one is exposed for a long period of time.
The Germans, at the battle of Ypres, employed the first use of poisonous gas.
Germans bombarded the French and Algerian troops, when soon allied soldiers began to notice a yellow-green cloud drifting towards them.
The troops believed the gas was a distraction/disguise to hide the German ambush, so they stood their ground. The gas turned out to be chlorine gas, which destroys the lungs within seconds of inhalation.
The effects of the chlorine gas caused mass panic and confusion amongst the allied lines. The Germans were just as confused and surprised, and they missed their opportunity to attack.
Germany’s use of poisonous gas diminished it’s relations with neutral countries like the U.S. However, it also opened the door for poisonous gas throughout the rest of the war.
The British planned a retaliatory attack against the German forces, however their attempts were unsuccessful.
The British system of releasing gas was susceptible to wind shift, and on the day of the attack, gas was blown back on British forces.
Both sides eventually shifted from chlorine gas to a combination of chlorine gas and phosgene.
This new combination did not have the initial lethality of chlorine gas, but caused extreme coughing and choking.
The effects of Phosgene gas poisoning had a delayed effect, and was known to kill soldiers some 48 hours later.
The Germans led in victories with poisonous gas attacks and were the first to employ mustard gas against the Russians.
Mustard gas is an almost odorless gas and resulted in serious blisters inside and on the exterior of the body.
Protection against mustard gas proved more difficult then any other.
Mustard gas stayed potent in any soil for weeks. Any trench that was gassed previously was just as dangerous to try to overtake after the attack.
As fast as new poisonous gas was being produced, new protection was following it.
Poisonous gas initially took many lives, but once the element of surprise was gone, the death toll quickly diminished.
Gas masks and respirators became normal issued gear for wartime.
In 1918, Harry S. Truman, before he was president, was the captain of a U.S. field artillery unit that used poisonous gas against the Germans. In 1917, the US developed and used their own chemical weapons.