Marxism as a theory of history

Marxism, or dialectical and historical materialism, has served as both the major explanatory theory of history and social development and the theoretical basis for socialist and communist movements from the late 19th century to today
Write an essay that answers and ties together the following questions concerning Marxist socialism’s general theory and the achievements and failures of the movements for socialism up to the 1917 Russian Empire Socialist Revolution.
Part One:
What roles do material conditions, modes of production/ stages of development, and class consciousness play in Marxism as a theory of history?
What are the roles of class struggle and revolution in Marxism as a theory of history and social development? What are the different kinds of revolutions that Marxism sees in history?
Why, in Marxist theory, must capitalism be replaced by socialism for civilization to advance in a positive direction? What criticisms, both positive and negative would you make of Marxist theory based on your knowledge of history?
Part Two:
What major victories and defeats had the socialist movement made from Marx and Engels writing of the Communist Manifesto in 1848 to 1917, WWI and eve of the Soviet Revolution?
How had issues of nationalism, racism, and imperialism affected the development of the socialist movement?