Fritz Wächtler was born in 1891 in Triebes, in the Principality of Reuss-Greiz (present-day Thuringia), the son of a watchmaker. Between 1905 and 1911 he attended the Weimar Lehrerseminar, a special training academy for primary school teachers. After two years of teaching activity and military service, in 1914 he became a "one-year volunteer" (German: Einjährigfreiwilliger) on the front during World War I. By 1915 he had been promoted to lieutenant.