The League had originally followed Wilhelm Weitling's lead, but in the 1840s it came under the influence of Karl Marx and Friedrich Engels. Schapper became head of the 'Communist Correspondence Committee' and organised the publication of Marx' and Engels' Communist Manifesto in 1848. Schapper also contributed to the Communist Journal (Kommunistische Zeitschrift) published by the League. He is thought to have been the author of an anonymous commentary on the Communist ManifestoCp. Henderson, W.O., The life of Friedrich Engels. Volume 1. London, 1976, p. 118. and polemicized against the radical democrat Karl Heinzen.
