Friedrich Engels has often been credited with composing the first drafts which led to the Communist Manifesto. In July 1847, Engels was elected into the Communist League, where he was assigned to draw up a catechism. This became the Draft of a Communist Confession of Faith. It contained almost two dozen questions that expressed the ideas of both Engels and Karl Marx at the time. In October 1847, Engels composed his second draft for the League, The Principles of Communism (which went unpublished until 1914). Once commissioned by the Communist League, Marx combined these drafts with Engels' 1844 work The Condition of the Working Class in England to write the Communist Manifesto.
Although the names of both Engels and Marx appear on the title page alongside the "persistent assumption of joint-authorship", Engels, in the preface to the 1883 German edition of the Manifesto, said it was "essentially Marx's work" and that "the basic thought... belongs solely and exclusively to Marx." Engels wrote after Marx's death:
I cannot deny that both before and during my forty years' collaboration with Marx I had a certain independent share in laying the foundations of the theory, but the greater part of its leading basic principles belongs to Marx ... Marx was a genius; we others were at best talented. Without him the theory would not be by far what it is today. It therefore rightly bears his name.
Despite Engels's modesty in this quotation, he made major contributions to the Manifesto, starting with the suggestion to abandon "the form of a catechism and entitle it the Communist Manifesto." Moreover, Engels joined Marx in Brussels for the writing of the Manifesto. There is no evidence of what his contributions to the final writing were, but the Manifesto bears the stamp of Marx's more rhetorical writing style. Nevertheless, it seems clear that Engels's contributions justify his name's appearance on the title page after Marx's.