Born in Westphalia in 1820, Friedrich Engels was the son of a textile manufacturer. After military training in Berlin and already a convert to communism, Engels went to Manchester in 1842 to represent the family firm. A relationship with a mill-hand, Mary Bums, and friendship with local Owenites and Chartists helped to inspire his famous early work, The Condition of the Working Class in England in 1844. Collaboration with Marx began in 1844 and in 1847 he composed the first drafts of the Manifesto. After playing an active part in the German revolutions, Engels returned to work in Manchester until 1870, when he moved to London. He not only helped Marx financially, but reinforced their shared position through his own expositions of the new theory. After Marx’s death, he prepared the unfinished volumes of Capital for publication. He died in London in 1895.

Karl Marx was born in 1818 in Trier, Germany and studied in Bonn and Berlin. Influenced by Hegel, he later reacted against idealist philosophy and began to develop his own theory of historical materialism. He related the state of society to its economic foundations and mode of production, and recommended armed revolution on the part of the proletariat. Together with Engels, who he met in Paris, he wrote the Manifesto of the Communist Party. He lived in England as a refugee until his death in 1888, after participating in an unsuccessful revolution in Germany. Ernst Mandel was a member of the Belgian TUV from 1954 to 1963 and was chosen for the annual Alfred Marshall Lectures by Cambridge University in 1978. He died in 1995 and the Guardian described him as 'one of the most creative and independent-minded revolutionary Marxist thinkers of the post-war world.'