He was excluded from conscription during the First World War on health grounds. The 1914 decision of the party's parliamentary leadership in to vote in favour of war funding had been contentious from the outset, and anti-war sentiment among the party membership was intensified by the extent of the slaughter on the frontline and the acute economic hardship on the home front. In 1917 the party broke apart over the issue, and Schubert was part of the substantial breakaway minority that formed the anti-war Independent Social Democratic Party. Directly after the war ended in military defeat, triggered by the Kiel mutiny and inspired by the so-called "October Revolution", revolution spread quickly across Germany during November 1918. In Zwickau Schubert assumed a leadership role in the workers' and soldiers' soviet which fought for power locally between November 1918 and January 1919. During January 1919 he was a co-founder of the Zwickau Spartacus League, and by the middle of January 1919 had emerged as the (first) chairman of the Zwickau Communist Party.&lt;ref name=1918/19lautZ&gt;&lt;/ref&gt;