So, chlorine has not been historically used as a chemical weapon. This would be news to a lot of people who were at Ypres in 1915:
But Obama is right -- it's also why whenever there's a chlorine leak from a municipal swimming pool facility, we don't even worry about it.After the batteries were in place, it was decided that wind conditions and the ragged configuration of the front line in that sector made it unsuitable for a gas discharge. New batteries of gas cylinders then were dug in along the northern flank of the salient, the batteries being concentrated at Bixschoote, near the junction between the northern flank of the salient and the front north of Ypres, and at Poelkapelle, near the apex of the salient. On April 11, the batteries were in place on the north flank, ready to deliver about 150 tons of chlorine gas on order. An attack was planned to follow behind the gas cloud, along a southern axis to sweep across the base of the salient, with the Bixschoote-Poelkapelle front as the line of departure for the German assault force.After several postponements, always awaiting suitable wind conditions, the attack finally was ordered at 5:30 p.m. on April 22, 1915. What followed staggers the imagination.As seen by the Canadians, who stood to the right of the Algerians, two greenish-yellow clouds formed on the ground and spread laterally to form a terrifying single cloud of bluish white mist. Blown by light wind, the cloud moved down on the Algerian trenches. The Canadians noticed a peculiar odor, smarting eyes, a tingling sensation in the nose and throat, and heard a dull, confused murmuring underlying everything.Soon, Algerian stragglers began to drift toward the rear, followed by horses and men pouring down the road and finally by mobs of Algerian infantry streaming across the fields, throwing away their rifles and even their tunics. One Algerian, frothing at the mouth, fell writhing at the feet of the British officer who tried to question him.Sir John French, commander of the British Expeditionary Force, later said: What happened is practically indescribable. The effect of the gas was so overwhelming that the whole of the positions occupied by the French divisions was rendered incapable of any resistance. It was impossible at first to realize what had actually happened. Fumes and smoke obscured everything. Hundreds of men were thrown into a stupor, and after an hour the whole position had to be abandoned with fifty guns.As seen by the Germans, the effects of the attack were horrible, the dead lying on their backs with clenched fists, the whole field bleached to a yellow color.
For further context, see First Ringer's excellent essay on the subject of the chlorine gas attack at Ypres and its aftermath, which he published at Shot in the Dark a few weeks back. Maybe our President could learn something from it.