 Chemical mortar battalions used the 4.2-inch chemical mortar to support armor and infantry units.During all parts of the war, use of chemical and biological weapons were extremely limited by both sides.Italy used mustard gas and phosgene during the short Second Italo-Abyssinian War, Germany employed chemical agents such as Zyklon B against Jews, political prisoners and other victims in extermination camps during the Holocaust, and Japan employed chemical and biological weapons in China.