Marx's conception of history is called historical materialism. It is the idea that material conditions are the basis of development of human history. What this means is that society is developed through the sharpening of contradictions between classes in different economic formations. Marxist historiography, therefore, focuses on the development of these contradictions by looking at the underlying class struggles.

/u/ardenincascadia presented a basic, but somewhat incorrect, explanation in the context of the French Revolution. I think it would be helpful to correct some of what he said and in order to present the Marxist method more clearly.

A Marxist would look at the Revolution and say that it occurred because the privileged upper-class, including the monarchy, the nobility, and the clergy (the First and Second Estates) were struggling with everybody else (the Third Estate).

A Marxist views things in terms of economic classes and in the French Revolution there were three - The aristocracy (the feudal land-owning class), the proletariat (the fledgling class of wage-workers) and the bourgeoisie (the growing capitalist class). Both the bourgeoisie and the proletariat were represented in the Third Estate, which at first seems paradoxical since Marxism is founded upon the idea that the workers struggle against the capitalists. The solution lies in the fact that Marxism is a philosophy of development, that the contradiction in the French Rev. was between the bourgeoisie and the aristocracy since capitalism's contradictions had not been developed yet.

It is an issue of economic development for Marxists, not privilege and class.

For instance, many historians would say that the American colonies revolted against England because of unfair taxation (an economic reason). A Marxist would say that it was because the lower-class American colonists were fed up with oppression at the hands of the upper-class English colonizers, especially governors and colonial officials.

Unfortunately, this is more incorrect than the last example. A Marxist again views things in terms of economic development. A Marxist would look at the situation and say that American industrial capital had outgrown the hold of British finance capital and needed to shrug them off. Marx never spoke to imperialism in detail, but Lenin expanded on the subject, an interpretation that explains why Russia was the first Socialist state over an industrial center like Marx had predicted.

If you would like me to clarify, expand or explain more I would be happy to.

Marxists themselves did not call themselves Marxists. Their term of choice was "historical materialism". And they did not claim they had pioneered this approach. Plekhanov, a classical Marxist from the golden era, points out that Hegel in fact had to break with his idealism to talk about the historical conflicts that he knew anything about. That book of Plekhanov is called the Monist View of History.

Amongst academic historians the fashion for historical materialism died off roughly together with the USSR during what's now termed the "cultural turn". Nowadays they do prefer not Sociology and Economics but Linguistics and Philology to fill in the blanks. But who knows what the next big thing will be?

That said, I am not an academic historian myself. So wait till the real ones arrive.