The family company, known formally as Friedrich Krupp AG Hoesch-Krupp, was a key supplier of weapons and materiel to the Nazi regime and the Wehrmacht during World War II. In 1943, Krupp became sole proprietor of the company, following the Lex Krupp ("Krupp Law") decreed by Adolf Hitler. Krupp's wartime employment of slave labor resulted in the "Krupp Trial" of 1947–1948, following which he served three years in prison.