فريتز هابر
In 1916 Fritz Haber, who was now the director of the Kaiser Wilhelm Institute for Physical Chemistry and Electrochemistry ("KWIPC", today the Fritz Haber Institute of the Max Planck Society) in Berlin, invited Steinkopf to join his institute as the head of a team devoted to research on chemical weapons. Together with chemical engineer Wilhelm Lommel, Steinkopf developed a method for the large-scale production of bis(2-chloroethyl) sulfide, commonly known as mustard gas. Mustard gas was subsequently assigned the acronym LOST (LOmmel/STeinkopf) by the German military.