Born in Timișoara (known then as "Temeschwar" or "Temesvár"), Wilhelm Stepper-Tristis belonged to an old family of Jewish merchants. Soon after receiving his "matura" at age 18, he enrolled in the Austro-Hungarian Army and took part in World War I, being sent to the Italian Front. He fought in the Battles of the Isonzo, and specifically in the Battle of Gorizia.