Gás Mostarda

"In July 1917 the English troops near Ypres were fired upon by the Germans with shells which contained an oily liquid. Those who came into contact with this oil developed a few hours later symptoms previously unknown. The new chemical warfare agent caused burns on the skin that were slow to heal; it quickly penetrated clothing and it contaminated the ground. A new stage began in chemical warfare; the use of persistent chemical warfare agents of long-lasting effect." [5]