Schumann's father was a socialist. The skilled toolmaker joined the Social Democratic Party of Germany (SPD) in 1905, and was chosen to be shop steward in Jena in 1907. In 1912, attended the Social Democratic Party School in Jena, where Rosa Luxemburg discovered his journalistic gift. The SPD posted him at the "Leipziger Volkszeitung" newspaper in 1913 as editor. During World War I, Schumann joined the "Gruppe Internationale" (see "Spartacist League") founded by Luxemburg, Karl Liebknecht and Clara Zetkin and agitated in the "Leipziger Arbeiterjugend" (Leipzig Working Youth) against the war. In 1916, he was conscripted, and for doing illegal work for the Spartacist League within the army, he was sentenced to hard labour imprisoned for 12 years but freed by the November revolution.