In 1810 Friedrich Krupp, 1787-1826, built a small steel plant at Essen. His son, Alfred Krupp, 1812-87, the cannon king, specialized in armaments and acquired mines all over Germany. Under Alfred's son, Friedrich Alfred Krupp, 1854-1902, the family extended its operations. The husband of his daughter, Bertha Krupp (after whom the Big Bertha guns were named), took the name Gustav Krupp von Bohlen und Halbach, 1870-1950. He took over what was then a public company and made it the center of Nazi rearmament in the 1930s. In 1943, Hitler converted the company back into a family holding, and Alfred Krupp von Bohlen und Halbach, 1907-67, son of Gustav and Bertha, ran the company until the end of World War II. He was convicted (1948) as a war criminal but was released from prison (1951) and allowed to resume control of the firm.