Mustard gas was introduced by Germany at Ypres on the Westrern Front.
History paints a different picture of Emperor Karl I :
"...by the death of Franz Josef in late 1916; he became Austrian Emperor (Kaiser) on 21 November, and King of Hungary on 30 December. Acutely aware that Austria-Hungary's entry into the First World War (having essentially brought it about) was likely to prove the undoing of the empire, Karl quickly sought a means of negotiating a separate peace with the allies. ....................Regarded as weak by both political extremes, left and right, Karl nonetheless drew support from political moderates. Karl responded with the appointed of a succession of liberal, reformist prime ministers, pretty much reflecting his own views. Similarly determined to reform the army, Karl banned flogging, ended duels, called a halt to strategic bombing and limited the widespread use of poison gas; which served merely to infuriate his high command.