Some of them even believe, departing even further from what Marx wrote, that you need not have capitalism before you can have socialism. The Materialist Conception of History Marx never used the term dialectic materialism nor did he ever argue that history was all down to economics, even less that the historical process was down to the instruments of production. This is in essence Marxs view of history although it is, we should remember, a simplification. The Communist Manifesto was meant for mass consumption and as a result Marx had to put his point across in a very simple manner. What he basically meant was that class struggle, those actions that result from antithetical class interests, lead to social change.
Classes have to fight it out, often literally, in order to usher in their mode of production.
The emrging ruling class cannot become the ruling class unless its mode of production, be it feudalism or capitalism, is the dominant mode of production within a given society. The ruling class always resist any changes that bring about such a situation while the emerging ruling class always fights for those conditions that foster the development of their mode of production. The result is class struggle. Marx was also, as you may or may not know, a materialist. The mode of production of material life conditions the social, political and intellectual life process in general.