After the end of World War I, which he experienced between 1914 and 1917 as a lieutenant, awarded the Iron Cross First Class (EK I), first on the Eastern Front, and later until his captivity in April 1917 in France, Osthold began studying political science in Königsberg in 1921. Before he received his doctorate in political science in 1926 in Münster with a thesis on the relationship between Marxist socialism and German state thought in World War I, Osthold had been heavily involved in the German national movement in addition to his professional activity. As a member of the Stahlhelm, which was known to be closely related to the DNVP, he had inter alia participated in the Ruhrkampf. Here he belonged to the underground resistance against the French occupation forces until the end of 1923, which was also supported by members of the Freikorps. After the end of the Ruhr struggle, Osthold went into politics, where he became involved in the DNVP founded by Alfred Hugenberg. In the election for the Reichstag in May 1924, from which the party emerged as the second strongest force with 19.5 percent, he narrowly failed to enter parliament. In the rest of the Weimar period, Osthold worked primarily as managing director of DINTA. In this function he wrote the popular work "The Struggle for the Soul of Our Worker" in 1926, which historians consider the institute's political manifesto and a continuation of Chancellor Hans Luther's considerations on the "Influence of modern large-scale economy on religion" from 1925. Osthold’s much acclaimed work is characterized above all by the author's preference for the economic forms and industrial relationships established in the USA, which Osthold sought to transfer to Germany.