The "Manifesto of the Communist Party" was written by Marx and Engels as the Communist League's programme on the instruction of its Second Congress (London, November 29-December 8, 1847), which signified a victory for the followers of a new proletarian line during the discussion of the programme questions.
When Congress was still in preparation, Marx and Engels arrived at the conclusion that the final programme document should be in the form of a Party manifesto (see Engels' letter to Marx of November 23-24, 1847). The catechism form usual for the secret societies of the time and retained in the "Draft of a Communist Confession of Faith" and "Principles of Communism," was not suitable for a full and substantial exposition of the new revolutionary world outlook, for a comprehensive formulation of the proletarian movement's aims and tasks. See also "Demands of the Communist Party in Germany," issued by Marx soon after publication of the Manifesto, which addressed the immediate demands of the movement.
Marx and Engels began working together on the Manifesto while they were still in London immediately after the congress, and continued until about December 13 when Marx returned to Brussels; they resumed their work four days later (December 17) when Engels arrived there. After Engels' departure for Paris at the end of December and up to his return on January 31, Marx worked on the Manifesto alone.