Berthold was born in Hindenburg (as Zabrze had been renamed) after 1914). Hindenburg was a substantial manufacturing city in Upper Silesia: the 1921 plebiscite had identified it as a predominantly German-speaking city, albeit by a narrow margin. Lothar Berthold's father worked as a customs official. After completing his school final exams (Abitur) at a relatively young age, in 1943/44 he became a Luftwaffenhelfer ("loosely: "air defence assistant""). In 1944 he was enrolled into the National Labour Scheme. Before the end of the year he had been conscripted into the army. He was briefly a member of the Nazi Party. By the time the war ended, in May 1945, he had already been promoted to a junior officer rank.