In 1848, with Friedrich Engels as his closest collaborator, he wrote the Communist Manifesto, which attacked the state as the instrument of oppression, religion and culture as ideologies of the capitalist class.

In 1849 he settled in London where he studied economics. Marx' main work "The Capital" is a critical analysis of the capitalist system.
Karl Marx interpreted history as a neverending struggle between classes which could only be resolved after a revolution would result in a dictatorship of the working class that would abolish the class system altogether.

His revolutionary ideas formed the foundations of communist parties all over the world.