Proudhon's theory of property as the right of aubaine is substantially the same as the theory of capital held by Marx and most of the later socialists.
Though I think Karl Marx overestimated its importance when he identified this conflict as the fundamental struggle of history, it certainly has been a constant.
Studying the writings of Karl Marx he became a convert to an extreme revolutionary, socialistic and atheistic creed; but though he entered into correspondence with Marx, with the object of starting a revolutionary movement, he does not appear to have taken any overt part in the events of 1848-1849.
The Weisskunig was long regarded as the work of the emperor's secretary, Marx Treitzsaurwein, but it is now believed that the greater part of the book at least is the work of the emperor himself.
It was in conjunction with Marx and Laf argue that he drew up the programme accepted by the national congress of the Labour party at Havre in 1880, which laid stress on the formation of an international labour party working by revolutionary methods.
At the Hague congress of the International in 1872 he was outvoted and expelled by the Marx party.
Plekhanov and Struve were at that time the chief exponents of Marxism: they adopted the teaching of Karl Marx as regards the necessary sequence of economic stages - feudalism, bourgeois individualism, capitalism, proletarian upheaval.
With Liebknecht he belonged to the branch of the socialists which was in close correspondence with Karl Marx and the International, and refused to accept the leadership of Schweitzer, who had attempted to carry on the work after Lassalle's death.
We can't resolve the ambivalence in Marx -- or at least in possible interpretations of Marx.
In Paris Ruge tried to act with Karl Marx as co-editor of the Deutsch-Franzosische JahrNicher, but had little sympathy with Marx's socialistic theories, and soon left him.