Jabberwalker Jabberwalker:
toughened up and ready enough to stand their ground in the face of the first WMD attack in history when it occurred against them.
Umm, not exactly.
$1:
1915: Large-scale use and lethal gases
The first instance of large-scale use of gas as a weapon was on 31 January 1915, when Germany fired 18,000 artillery shells containing liquid xylyl bromide tear gas on Russian positions on the Rawka River, west of Warsaw during the Battle of Bolimov. However, instead of vaporizing, the chemical froze and failed to have the desired effect.
Let's call it the first gas attack that worked.