Marx wrote about his disagreement with the free enterprise system in

Marx wrote about his disagreement with the free enterprise system in Das Kapital
Das Kapital is considered the most important book and opus magnum of Marx which was fundamental for socialist and communist ideology, published in 1867 in Hamburg. Das Kapital was a reasoned carefully researched treatise based on Marx saw as the inevitably ongoing class conflict between bourgeoisie and proletariat. Marx agreed with Hegel on the need for a driving impetus but disagreed about this impetus. Marx envisioned a world of a continually evolving materialism that forced human beings to remain in eternal conflict. As a result, in The Communist Manifesto and Das Kapital, Marx boldly announced that he had found Hegel standing on his head and was determined to swap his head with his feet. This "swapping" forms the basis of the three volumes of Das Kapital.

from the conditions of the working class in england by friedrich engels,the main idea is :

manchester's leaders hoped to oppress its working class to benefit factory owners.